Art. XLVIII.—On the Leaf-structure of some Plants from the Southern Islands of New Zealand.
[Read before the Philosophical Institute of Canterbury, 5th July, 1905]
Communicated by Dr. Charles Chilton.
The Southern Islands of New Zealand consist of several groups of small islands—namely, The Snares, Auckland Islands, Campbell Island, Macquarie Island, Antipodes Islands, and Bounty Islands—lying in the South Pacific Ocean between the parallels of 54° and 47′ south latitude, and 159° 49′ and 179° east longitude. They all lie in a more or less southerly direction
from the South Cape of Stewart Island, the southernmost point of New Zealand. The Snares are 60 miles to the south-west, the Auckland Group 190 miles south by west, Campbell Island 330 miles south by east, Macquarie Island 570 miles south-west by south, the Antipodes Islands 490 miles east-south-east, the Bounty Islands 490 miles east.
These islands present an exceedingly interesting flora for the study of the botanist. First, it occupies an important position because of the light it throws upon the history of the flora of New Zealand itself. Dr. Cockayne (1903) considers that here are preserved remnants of an old vegetation which at one time spread more widely over the whole of New Zealand, and also further south in previous land connections. Now, whatever may have been the case in past ages, these islands are far removed from any other large tracts of land, and consequently, where natural conditions have not been disturbed, they retain their primitive flora intact.
Again, in certain parts, especially on Campbell Island, man has recently made settlements and introduced a disturbing element by seeking to “reclaim” certain portions of the island. Here, then, is afforded to the botanist an excellent opportunity of finding out “the general laws that govern such vegetation-modifications, for the gradual changes from purely virgin formations to final reclamation can be observed and the factors bringing this about noted.”* Then, again, these islands are the homes of certain remarkable plants which are found here and nowhere else, such as Stilbocarpa polaris, the species of Pleurophyllum, and Olearia lyallii.
The only opportunity the botanist has of visiting these islands—excepting, of course, the special opportunities afforded by scientific discovery expeditions—is by accompanying the Government boat on her trip round the outlying lighthouses and islands to leave stores, &c. This trip is made twice a year, once in winter and again in summer. The weather is often very rough and makes landing difficult; Snares Island is sometimes not visited for this reason. Then, again, on a trip such as this the time allotted to each stopping-place is necessarily very limited, and much has to be done in the way of making notes, collecting material, &c., in an all-too-short time.
Previous to 1903 the botanical visits to the islands had all been made during the summer trip of the boat, and there are several accounts of the summer aspect of the vegetation from various botanists, the fullest being by the late Professor T. Kirk.†
[Footnote] * Cockayne (1903), p. 301.
[Footnote] † “On the Botany of the Antarctic Islands” (1891).
Last year, however, Dr. Cockayne accompanied the boat on its winter trip, and the results of his investigations have been published in the “Transactions of the New Zealand Institute.”* This paper gives much the fullest description of the different plant formations, as regards their nature and extent, and is a very valuable addition to the history of the botany of New Zealand. There is some detail given of the more important plants concerning their adaptability by their structure to their surroundings, and in some cases a hasty description of the anatomical structure is given. In this paper I propose to go more fully into the anatomical structure of the leaves of certain of these plants, to show in what way the plant adapts itself to meet the peculiar conditions of the climate. The leaf is the organ chiefly affected in cases of this kind, since the most urgent need of the plant is that it should be able to obtain or retain a sufficient supply of moisture. This induces the so-called xerophytic characters which are mainly met with in the leaf.
The material on which I have been able to work has been growing ready to my hand. Dr. Cockayne, during his visit to the islands, succeeded in making a very valuable collection of living plants, and this he has very kindly presented to the biological laboratory of Canterbury College for its rockery. The rockery was built last year, under Dr. Cockayne's supervision, for the cultivation of alpine plants. It is situated on the south side of the laboratory, and is thereby protected to a considerable extent from the sun. The plants of the Southern Islands have been placed on the shadiest portion of the rockery, so that they will get very little sun indeed. This, as will be seen from the description of the climate prevalent of the islands, is a necessary factor to insure their satisfactory growth, for we find that the sun is seldom seen there. Most of the plants have taken very kindly to their new surroundings, and are flourishing well; some few have been unable to maintain an existence in the absence of certain peculiar characteristic constituents of their habitat, and have perished.
In all, twenty-nine species of flowering-plants were examined, a list of which is given later on. This was all I had time to examine, and includes most of the species on the rockery. The more important and striking of the plants I have endeavoured to describe more fully.
In a study of this nature there are two factors which must be considered as most important in determining the character of the plant: these are (1) the climate, and (2) the soil.
[Footnote] * “A Botanical Excursion during Midwinter to the Southern Islands of New Zealand.”
1. Climate.—All the islands seem to resemble one another very closely in respect of climate. First of all, Hooker notices, in his “Flora Antarctica” (vol. i, xi), “that the vast proportion which the water bears to the land tends to render the temperature more uniform throughout the year—the further south the position the more equable the climate seems to be… The power of the sun is seldom felt, and, unless in the immediate neighbourhood of land and accompanied by a comparatively dry wind, that luminary only draws up such mists and fogs as intercept its rays… All the islands to the south of 45° partake more or less of this inhospitable climate, which, though eminently unfavourable to a varied growth of plants, still, from its equable nature, causes a degree of luxuriance to pervade all the vegetable kingdom, such as is never seen in climates where the vegetative functions are suspended for a large portion of the year.”*
The climate of the Auckland Islands, he says, is “rainy and very stormy” (p. 2). Dr. Cockayne sums up the features with regard to the climate of the Auckland Islands as follows: “(1) There are a great number of rainy days; (2) the moisture, which can easily permeate the peaty soil, will not readily evaporate owing to the almost constant cloudy skies, these also tending to keep the air full of moisture; (3) there are very frequent winds, sometimes of great violence, accompanied by rain or sleet; (4) the winter climate is extremely mild—much milder, indeed, than that of certain parts of the South Island of New Zealand at sea-level, as, e.g., the Canterbury Plains” (pp.235–6).
The climate of Campbell Island is very similar: “There is the same lack of sunshine and similar frequent gales accompanied by driving rain and sleet, especially in spring and autumn.… Sunshine is most frequent during the summer months.… The snowfall at sea-level is very slight… comes in blasts from the south-west, while these gales are frequently accompanied by hail.… In the ‘subalpine region’ the frost is much stronger… there was no general covering of snow… such frosts… subject these plants to comparatively severe conditions.” (p. 268). Here are found, amongst other plants, Coprosma repens, Epilobium confertifolium, Phyllachne clavigera.
“As for rain, really heavy rain is not very frequent; usually it is a fine drizzle. In short, there must be a great number of rainy days, but no excessive annual rainfall” (p. 269).
“With regard to the climate of the Antipodes Island, I should imagine that it is very similar to that of the other South-
[Footnote] * Hooker (1847), “Summary of the Voyage,” vol. i, xi.
ern Islands—cloudy skies, frequent showers, a mild temperature in winter but a cool summer, and, finally, furious gales and squalls with hail or sleet, of which winds the nature of the arborescent plants bears abundant evidence” (p. 285).
On the Bounty Islands there is no vegetation except “an alga clothing the rocks and giving them a greenish hue in places, and on the rocks a mass of a peculiar species of Durvillœa” (p. 297). The prevailing conditions of climate are therefore well summed up in the above description of the climate of Antipodes Island.
The temperature is pretty uniform throughout the entire year, and active growth is possible for the greater portion of the year. There is very little sunshine, the sky being usually cloudy, and when there is no actual rain the atmosphere will contain considerable moisture. All the islands are subject to rather severe gales, and this has an effect on the number and appearance of the ligneous plants present. On Snares Island and Auckland Islands there is a pretty extensive forest formation, but on Campbell Island, in consequence of severer winds, it is merely a scrub formation; on Antipodes Islands the scrub is even less developed, while on Macquarie Island there is none at all.
2. Soil.—The second important factor which influences the form and structure of plants is the nature of the soil in which they grow; and we find the different soils characterized by different formations or associations of plants in which some one plant or more predominates and gives its especial character to the formation. Here, again, following Dr. Cockayne's classification, we get the following formations: (1) Sand-dunes, only on Auckland Island; (2) coastal rocks; (3) forest in Auckland Islands and Snares, scrub in Campbell and Antipodes; (4) lowland tussock; (5) meadow formations; (6) bog in Antipodes Islands; (7) subalpine—(a) meadow, (b) rocks.
Full details of these formations are to be found in Dr. Cockayne's paper of 1903 (p. 226).
The soil in which these plants of the Southern Islands find themselves situated is therefore generally of a moist peaty nature, and not one which at first sight calls for modifications to check the amount of water transpired; but an examination of the chemical composition of such a soil shows that it must necessarily consist of various salts, which the water to be taken into the roots will dissolve. In swampy districts, also, there is a great percentage of humic acid present, and this is harmful when taken into the tissues of the plants. In the first case, “salts that are dissolved by the water in the soil influence the osmotic processes, and consequently the absorption of
water.”* This is just a natural application of the laws ruling the phenomenon of osmosis. When the root absorbs water with difficulty it is necessary to reduce the amount transpired from the leaves, and hence those modifications of the leaf to check transpiration. The soil is also usually poor in oxygen, and this added to its acid character renders absorption of water difficult, and again necessitates the xerophytic character in the leaf. “The water-capacity of a given soil does not enable us to judge of the quantity of water that a certain plant is capable of taking from it.” *
In considering the adaptability of the plants to their environment, I will first of all deal briefly with some common features of external form which aid the plant in its struggle.
The strong winds to which certain parts of the islands are subjected must necessarily have a corresponding effect in determining the nature of the plants. Thus, for instance, there is an absence of any arborescent species on Campbell Island and Antipodes Islands, where there is greater exposure to such gales than on the Snares and in the Auckland Group. The trees that are present show the direction from which the winds come in the stunted branches on the windward side. The small species of the Coprosmas which occur on all the islands except Macquarie and Bounty Islands show the tendency to avoid exposure to the winds by their prostrate habit. Amongst the herbaceous plants, a large proportion form rosettes of leaves, which, pressed closely to the substratum, are able to resist the dislodging effects of furious gales. The huge plants of Pleurophyllum have adopted this habit, and form wide-spreading rosettes “which cover acres.” The smaller genera, Abrotanella, Cotula, Gentiana, Myosotis and Plantago, may also be classed here. Others have prostrate stems creeping over the ground and rooting at intervals; amongst these may be mentioned Epilobium, Cotula, and Pratia. Others, again, as the grass-like forms, Luzula, Scirpus, Carex, and Poa, are able to withstand any ill effects from the wind by their thin, linear, and pliant leaves. The larger herbaceous plants, as the two species of Ligusticum and the large-leaved Stilbocarpa, are able by the stout and firm structure of their leaves to resist the wind.
The modifications of the leaf itself to check transpiration may be enumerated as follows (following chiefly Kearney's classification, 1900, p. 279):—
A reduction in the transpiring surface, in the two species of Coprosma.
The position of the transpiring surface—modification
[Footnote] * Schimper (1903), p. 85.
common in the grasses and sedges, also in Astelia and Luzula, and in the spiral leaves of the young shoots of Epilobium. Under this head also may be classed the peculiar cushion-like plants of Colobanthus and Phyllachne.
The anatomical modifications of the epidermis of the leaf itself. (a.) A well-developed cuticle. This may be smooth or strongly wrinkled. A wrinkled cuticle serves the purpose of reflecting the light-rays, so that they do not strike down directly on to the chlorophyll tissue below. Such a cuticle is found in Ligusticum and Coprosma, amongst others. In Acœna and Poafoliosa the same purpose is answered by the peculiar outgrowth of the epidermal cells into short papillæ, which are provided with greatly thickened outer walls. (b.) The great development of hairs as outgrowths of the epidermal cells (Myosotis, Olearia, Ranunculus, &c.), or of the deeper tissues, as in Stilbocarpa. (c.) The position of the stomata.
Succulence of the leaf. “A succulent plant loses water much less readily, since the water-tissue gives up its supply reluctantly. In some cases succulence is due to the presence of mucilaginous slime in the cells of the water-tissue, which greedily absorbs and tenaciously retains water.”* Here may be classed the bog xerophytes, Colobanthus subulatus and Phyllachne clavigera, and also Epilobium, Ranunculus pinguis, Myosotis, and Astelia.
Structure of the chlorenchyma. In the majority of the plants examined the palisade tissue was strongly developed, consisting of from two to three layers. In Ligusticum antipodum, Phyllachne, Astelia, and Scirpus it is not developed, but its place is occupied by a more or less compact tissue composed of rounded cells, which probably acts in something the same way.
Presence of oil. Oil-globules are found in the mesophyll tissue, and sometimes in the epidermal cells of the two species of Coprosma, Olearia, Veronica benthami, and Astelia. It has been suggested that the secretion of ethereal oils aids the plant in resisting the ill effects of a heated atmosphere, since “minute quantities of such oils diffused through the air are capable of arresting radiant heat.”†
Another modification of interest in the leaf-structure is the development of stereom tissue. This is seen best in the species of Ligusticum. It gives rigidity to the leaves, and probably is a protection against the mechanical effects of the wind. In some other species it is developed in connection with the vascular bundles, as in Acœna, Epilobium, Olearia, Luzula, and
[Footnote] * Kearney (1901), p. 367.
[Footnote] † See Henslow (1895), p.82.
Carex trifida, and it has been suggested that here it is probably a protection against loss of water by evaporation from the vessels.* In Ligusticum it is further reinforced by the development of collenchyma, usually in connection with the epidermis. Pierce (1903, p. 124) considers that this collenchymatous tissue is primarily formed as strengthening-tissue in young growing organs, and is afterwards made use of as water-storage tissue, by holding the drops of water in the interstices of the cell-walls.
Colourless parenchyma tissue, which probably acts to store water, is present in Ranunculus pinguis, and occupies the greater part of the tissue of the succulent plants, as Colobanthus and Phyllachne. It is also specially developed in Astelia. Calcium oxalate is developed in certain of the plants. In Colobanthus it takes the form of clusters of crystals, while in Epilobium and Coprosma repens, belonging to the Dicotyledons, they are needle-shaped crystals formed in groups as raphides; raphides are also present in Astelia. Raphides are usually associated with mucilage secretion.††.
Ranunculus pinguis, Hook. f.
“Radical leaves on short stout petioles, fleshy, rounded, reniform, deeply crenate, lobulate, 1 in. to 3 in. in diameter, veins reticulated in young plants. oblong and cuneate; cauline more or less cut.”‡.
Hab.—“Boggy places on hills, 1,000 ft. above sea to mountain-tops on Campbell Island, and rare in rocky places on Lord Auckland's Island.”§.
Dr. Cockayne (1903) mentions it only once in his account of the Campbell Island flora. He says (p. 283) that it is more or less plentiful in the rich peaty soil of the wind-sheltered hollows of the subalpine rock region. Such a station as this, he adds, “is very favourable for plants, since the very conditions are here present which experience had found essential for the cultivation of difficult alpine plants-viz., shelter, a porous soil, abundance of pure water, perfect drainage.”
R. subscaposus, another plant of the Southern Islands, occurs in this same subalpine rock region, but under less favourable conditions. Both it and another species, R. aucklandicus, are flourishing well on the rockery at the present time, while R. pinguis has now entirely disappeared. The leaf I examined was very young, only about ½ in. in diameter, and did not show the
[Footnote] * Kearney (1900), p. 282.
[Footnote] † Strasburger (1898), p. 72
[Footnote] ‡ Hooker (1867), p. 4
[Footnote] § Hooker (1847), vol. 1, p. 3
form of the adult leaf, but its anatomical structure is probably very similar. Young as it was, it presented some striking points of difference from the older leaves of the other two species, especially as regards its succulent habit.
Anatomy (figs., 1a, 1b).—There is a very thick but smooth cuticle (cut.) on the upper surface which gives the leaf its shiny appearance. Below this comes the upper epidermis (ep.), with its large and thick-walled cells interrupted at frequent intervals by stomata (st.). The walls are collenchymatous, staining blue on the application of chlor-zinc-iodine. The cells of the lower epidermis (l.ep.) are somewhat smaller and not so thick-walled. No hairs are present. The chlorenchyma (chlor.) is differentiated into palisade (pal.) and spongy (sp.), the spongy parenchyma occupying the greater area. The palisade tissue consists of the ordinary palisade cells in 3—4 layers, densely filled with chlorophyll corpuscles, giving the leaf its characteristic dark-green colour. In this young leaf the palisade tissue was continued in two layers above the small vascular bundles (v.b.) which occurred scattered through the spongy tissue. In the other two species the vascular bundles interrupt the green chlorenchyma with a mass of colourless cells. The spongy tissue (sp.) is very loosely arranged, leaving large air-spaces between the cells. In the central portion of the leaf the cells are large and sparingly filled with chlorophyll; some occur as colourless thin-walled parenchyma cells (par.). Adjoining the lower epidermis, however, the cells are much smaller and round, and also more abundantly filled with chlorophyll. The vascular bundles (v.b.) are each surrounded by a more or less sharply defined endodermis (endo.), and this is again surrounded with a layer of larger thin-walled and colourless parenchyma (p.s.) cells. Each bundle consists of xylem (xy.) on the upper surface and phloem (ph.) on the lower.
Here the effects of the moist or semi-aquatic habitat are seen in the development of larger air-spaces.
Ranunculus subscaposus, Hook. f., Fl. Antarc., i, 5.
“Radical leaves on slender petioles, 3 in. to 8 in. long, blade broadly triangular-ovate, slightly cordate, 3-foliate or 3-partite to base; leaflets cuneate at the base and more or less deeply incised or toothed, or rarely entire with margins deeply cut; cauline similar.”*
“Both petiole and lamina on both surfaces are densely clothed with appressed whitish hairs.”††
[Footnote] * Kirk (1899), p. 15.
[Footnote] † Cockayne (1903), p. 273.
Hab.—Campbell Island, “by margins of rivulets in the woods.”*
This plant has so far, like R. pinguis, been found only on Campbell Island. Is is found in great abundance by the side of the small streams running through the Dracophyllum scrub formation.† It occurs also in the moist peaty soil of the Rostkovia formation, and in the peaty hollows of the subalpine rock region (p. 282). The leaf differs from that of R. pinguis in thickness, being a little less than half. This is brought about by a reduction in the number of layers of palisade and spongy parenchyma. Another point of difference is the presence of unicellular hairs on both surfaces of R. subscaposus. This reduction in tissue is no doubt a direct consequence of the poorer nature of its habitat. This would also account for its wider distribution, and the ease with which it adapts itself to its new surroundings.
Anatomy (figs. 2a, 2b, 2c).—There is no cuticle distinguishable in this species. The upper epidermis (ep.) consists of large but thin-walled cells, some oblong, others cubical in transverse section. Hairs (h.) are present on both surfaces as unicellular prolongations of the epidermal cells, while the cells around the hair are arranged in a radiating manner, radiating outwards from its base (fig. 2b, ep.). The lower epidermis (l.ep.) is composed of smaller cells, interrupted by numerous stomata (st.), which occur on this lower surface alone—another point of distinction from R. pinguis. The stomata project slightly from the surface of the leaf. The chlorenchyma (chlor.) is differentiated into palisade (pal.), consisting of one layer of large cells, widest at their junction with the upper epidermis, but gradually becoming narrower as they adjoin the spongy tissue (sp.). This is loosely arranged in 2–3 layers, and consists of smaller cells—some oblong, with their axis parallel to the surface of the leaf; others bordering on the lower epidermis are smaller rounded cells densely filled with chlorophyll. The air-spaces (a.s.) left between the cells of this tissue are also large and frequent. The main vascular bundles (v.b.) are situated beneath depressions of the upper leaf surface, and interrupt the chlorenchymatous tissue with their surrounding colourless cells. The smaller veins are scattered throughout the chlorenchyma. An endodermis (endo.) and parenchyma sheath (p.s.) can usually be recognised.
Ranunculus aucklandicus, A. Gray.
“Radical leaves strigose-hirsute, on slender petioles, 3 in.-5 in. long or more, slightly sheathing at the base, rounded reniform or the upper rounded truncate or almost subcordate, 1 in.–1 ½ in.
[Footnote] * Hooker (1864), p. 7.
[Footnote] † Cockayne (1903), p. 273.
in diameter, 3-cleft to or beyond the middle, mostly with a closed sinus, the broad lobes again 2–3-lobed or coarsely toothed.”*
Hab.—“Auckland Island, 1,800 ft.” (Kirk).
This plant is included in Kirk's account of the Campbell Island flora published in the New Zealand Transactions of 1881 (p. 387). There is no description of it in Dr. Cockayne's paper, but as there was a plant growing on the rockery I examined it for the sake of comparison with the other two species. It resembles most closely R. subscaposus.
Anatomy (fig. 3.)—There is no cuticle on either surface, and the cells of the lower epidermis (l.ep.) are slightly larger than those of the upper (ep.). There are stomata (st.) on both surfaces in this case, and long thick-walled unicellular hairs (h.). It resembles R. pinguis in having stomata on both surfaces, but R. subscaposus in all other respects, as, for instance, in the thickness of the leaf, presence of hairs on both surfaces, and absence of cuticle. The chlorenchyma (chlor.) is differentiated into palisade (pal.) of one layer, consisting of cells not so large as those of R. subscaposus, and spongy of 3—4 layers of elongated cells about twice as long as broad, arranged very loosely so as to leave numerous air-spaces (a.s.). This loose arrangement of spongy tissue is a characteristic feature of all these three species of Ranunculus, and is doubtless a direct result of the moist or semi-aquatic habitat,† to insure a sufficient aeration of the chlorophyll-containing cells of the chlorenchyma, without which assimilation is checked. The main vascular bundle, as in the case of R. subscaposus, lies below a depression of the upper leaf surface, and below it the lower epidermis (l.ep.) is strengthened by a double layer of collenchymatous cells (col.).
Colobanthus subulatus, Hook. f.
“A small, moss-like, densely cæspitose, perfectly glabrous plant, with subulate, rigid, shining leaves, forming tufts 1 in. high. Leaves densely imbricated, about ⅙ in. long, with acicular points, grooved above, convex on the back.”‡
“This plant forms small, convex, round, dense, soft cushions, about 5 cm. in diameter. At the ends of each shoot are 6—8 stout green leaves, about 7 mm. in length, the base membranous and sheathing, the apex acicular. The upper surface is channelled. Below the terminal green leaves the shoot-axis is clothed with the old leaves of previous years.”§
[Footnote] * Kirk (1899), p. 16.
[Footnote] † Henslow (1895), p. 144.
[Footnote] ‡ Hooker (1867), p. 25.
[Footnote] § Cockayne (1903), p. 284.
Hab.—“Campbell's Island; in rounded tufts on rocks near the summit of the hills, at altitude 1,000 ft.; of rare occurrence, and confined to the tops of the hills on Campbell Island; no-where seen in Lord Auckland Group. In the Falklands, and in Fuegia where it was discovered by Banks and Solander, it is very common, both on the low grounds and on the mountains.”*
This is one of the small rock-plants which find a habitation in the crevices of the rocks where a small amount of peat has been able to collect, while the moisture of the atmosphere makes life possible (fig. 4b).
The other species, Colobanthus muscoides, from which this one differs by being rigid and more pungent,* is more widely distributed throughout the islands. Below the green leaves of this species—that is, in the centre of the cushion—“the old leaves are all in a greater or less advanced stage of decay, and form a dense, yellow, sticky, peaty mass, about 10 cm. in depth, through which the shoot-axes penetrate, giving off at the under surface of the cushion a large number of fine roots. The peaty mass absorbs water like a sponge, and in the wet climate must nearly always be saturated with moisture.”†
In its natural habitat it is probable that Colobanthus subulatus behaves in the same manner, but on the rockery, where the conditions under which it has to live are not so stringent, the older leaves have not degenerated into the “sticky, peaty mass.” That it still maintains many of its xerophytic characters may be seen on a study of its anatomical structure.
Anatomy (figs. 4a, 4b).—There is firstly a thickened but unwrinkled cuticle, then come the epidermal cells, on the upper surface (ep.) very thick-walled but flattened, and on the convex side (l.ep.) still with thickened walls, but larger and more cubical in shape. There are numerous small stomata (st.) on the upper surface, with a few on the convex side just near the upper epidermis. The chlorenchyma (chlor.) may perhaps be said to be differentiated into palisade (pal.) and spongy (sp.). The palisade is found in three layers of small elongated cells on the upper surface, and for a greater or less distance is continued down the sides of the convex portion of the leaf. The rest of the leaf is composed of larger cells, more or less round in shape, containing very little chlorophyll. The chlorophyll is mostly confined to the palisade cells. There are two or three vascular bundles (v.b.) enclosed in a large thin-walled parenchyma sheath (p.s.) and imbedded in a mass of colourless thinwalled parenchyma (par.).
[Footnote] * Hooker (1847), p. 13.
[Footnote] † Cockayne (1903), p. 242.
Acæna sanguisorbæ, var. antarctica.
“The leaves are pale-green, but not whitish-green as those of A. sanguisorbœ var.pilosa, glabrous on upper surface but with many adpressed hairs on under surface. It may be distinguished at a glance from A. sanguisorbœ var. pilosa by the general aspect, which is chiefly brought about by the colour of the leaves,”* &c.
Hab.—This plant is found in Lord-Auckland Group, on Campbell Island, and also on Antipodes Island. On Auckland Island it forms part of the Pleurophyllum meadow formation, “trailing over the surface of the ground very abundantly in long shoots with its characteristic pale-green leaves.”†
On Campbell Island, where the land has been cleared for various purposes a new formation has arisen, and its most prominent member is Acœna sanguisorbœ antarctica, which is spreading so rapidly as to become a weed in the eyes of the farmer.
On Antipodes Island, again, it is spreading very rapidly. The albatros is very abundant on this island at certain times of the year, and where its nest occurs the primitive vegetation round has been destroyed. Dr. Cockayne found that “in nearly all cases Acœna and Stellaria were the first plants to make their appearance” (p. 299) in repopulating the bare places. The young albatros helps to distribute the plant. The seeds are matted in the down on its breast, and as it pushes its way down to the water they are rubbed off or scattered in the down. This plant forms a prominent feature of the tussock meadow, “climbing in thick masses over grass and fern” (p. 293).
On the rockery it is flourishing well, growing over the stones and other smaller plants, and, by reason of its large and peculiarly tinted leaves, forming quite a prominent member. Hairs are present on the lower surface of the leaf opposite the midrib and the more important veins, and also as small tufts at the apex of each tooth of the serrate margin.
It is quite distinct from A. sanguisorbœ pilosa, which is growing next it on the rockery—quite an insignificant member, completely overshadowed by its larger-leaved relative. The anatomical structures of the two present striking points of contrast, as may be seen by referring to figs. 5a and 5b.
Anatomy (figs. 5a, 5b, 5c, 5d, 5e).—There is no distinct cuticle, but the outer walls of the epidermal cells (ep.) of both surfaces bulge out to form short papillæ (pap.), and the outer walls of these cells are considerably thickened (ep.). In A.
[Footnote] * Cockayne (1903), p 319.
[Footnote] † Cockayne (1903), p. 259.
sanguisorbœ pilosa there are no papillæ, but the outer walls are straight (fig. 5d). The papillæ in this case probably serve the same purpose as the wrinkled cuticle of other plants, to reflect the light. They also affect the colour of the leaf. Stomata (st.) occur on the under surface, and are partially covered by the projecting papillæ of the neighbouring cells. The chlorenchyma (chlor.) is very sharply differentiated into palisade (pal.) and spongy (sp.), each consisting of two layers of cells. The distinction between the two tissues is so marked that a straight line parallel with either epidermis could be drawn between the two. In this respect also it differs from var. pilosa, where the two tissues pass gradually one into the other (fig. 5d). The palisade (pal.) consists of ordinary elongated cells with numerous chlorophyll corpuscles arranged along the side walls. The spongy tissue (sp.) is made up of regularly rounded cells with the corpuscles arranged on the upper and lower walls as seen in transverse section, usually 5 in each cell (fig. 5e). The chlorenchyma is interrupted at intervals by bands of colourless parenchyma cells (par.) enclosing the smaller vascular bundles (v.b.). The large midrib is found in the keel of the leaf surrounded by a mass of rounded and colourless parenchyma cells.
Epilobium confertifolium, Hook. f.
“Stem slender, creeping, ascending at the tips. Leaves small, suborbicular, densely foliaceous. Leaves opposite, often imbricating, rather fleshy, glabrous or glabrate, obovate-oblong, obtuse, shining, with few minute teeth, narrow at the base into a short broad sheathing petiole; minute hairs on the lower surface.”*
“A creeping plant, frequently forms rather dense patches on the surface of the ground; the old shoots are prostrate and dorsi-ventral, the leaves inserted on their flanks, the young shoots are raised above the ground, and the leaves are in a spiral. Roots about 4·6 cm. in length are given off here and there from the prostrate stem.”† (See fig. 6b.)
Hab.—“On grassy banks and in moist places.”‡ It is found on Auckland Island, growing on the sand-dunes and also on the shady sides of the gullies between them, extending to the top of the dunes, in association with a close turf of moss. “These dunes are traversed by deep gullies down which small streams of water flow, the drainage of the swampy ground above. These furnish plant-stations of considerable shade and moisture”; and
[Footnote] * Kirk (1899), p. 171.
[Footnote] † Cockayne (1903), p. 238.
[Footnote] ‡ Hooker (1847), p. 11.
it is here that Epilobium flourishes well.* It also occurs in the Pleurophyllum meadow of Auckland Island.
In Campbell Island it is mentioned in the subalpine tussock meadow, where the climate is much more severe than in the lower regions, owing to colder and longer frosts, greater exposure to the winds, to the smaller amount of sunshine, and almost constant presence of mist (p. 278). On the rockery this plant is spreading rapidly over rocks and soil, forming large patches of dark-green.
The change from spiral to dorsi-ventral arrangement of the leaves on the stem is very interesting. The creeping habit is a distinct advantage to the plant in its home on the sand-dunes, for by this means it is able to obtain a firm hold on the somewhat unstable surface; the leaves are then so twisted as to be exposed directly to the vertical rays of the sun when it shines on them, and they are further protected by a thick cuticle on the upper surface. The younger leaves, on the other hand, are more sensitive, and, being arranged spirally, catch the rays obliquely; and, as a further protection, anthocyanin is present in some of the epidermal cells. On the bleaker subalpine meadow of Campbell Island the creeping habit is also of great advantage in protecting the plant from the winds.
The leaf-anatomy of the younger and older leaves does not differ in any striking way, except in the presence of a cuticle in the older leaves which is absent in the younger ones, and in the presence of anthocyanin in the epidermal cells of the younger leaves.
Anatomy (figs. 6a, 6b).—The epidermal cells (ep.) consist of one layer of rather cubical cells, protected in the older leaves by a thickened but smooth cuticle. The transverse walls of the cells are thin. Stomata (st.) occur on both surfaces, projecting slightly from the surface. The chlorenchyma (chlor.) is differentiated into palisade (pal.) and spongy (sp.). The palisade (pal.) consists of three layers of oval-shaped cells, almost as broad as long, closely packed except beneath the stomata, and densely filled with chlorophyll corpuscles. The spongy (sp.) tissue is very loosely arranged with numerous intercellular spaces (a.s.); frequently chains of cells run parallel to the surface (see fig.). There are about six layers of these cells, and all are sparingly filled with chlorophyll. Bundles of raphides (r.) occur in certain of these cells. The chlorenchyma is interrupted by the mass of thick-walled collenchyma (col.) surrounding the main vascular bundle (v.b.), and beneath it is a mass of rounded parenchymatous
[Footnote] * Cockayne (1903), p. 237.
cells, filling up the ridge on the lower side of the leaf. This ridge is further strengthened by a double layer of thick-walled epidermal cells (l.ep.).
Ligusticum latifolium, Hook. f., Handbook
“Radical leaves 1 ft. to 2 ft. long or more; petioles sheathing at the base, sheath shortly ligulate, blade ovate excessively coriaceous 2-pinnate, segments obliquely cuneate below, with broad winged bases, unequally 3–5 lobed, lobes acuminate with acute points and thickened margins.”*
“Lateral segments not flat, but bent inwards, bringing the two surfaces into proximity, and the upper half in a vertical position with regard to light.”†
Hab.—Lord Auckland Group and Campbell Island; abundant in moist places.†
On Lord Auckland Islands it occurs “on the stony beach of Adam's Island, abutting on the Pleurophyllum meadow, and not much exposed to the sea-spray” (p. 240); also in the Pleurophyllum meadow itself it is found in splendid profusion owing to the favourable nature of the peaty soil, which is adapted for plant life. The peat is formed by the decaying leaves of Pleurophyllum, which afford a home for many earthworms. This causes a richer supply of oxygen in the soil, and a diminished quantity of humic acid.
On Campbell Island it is found also right down to the rocky shore, and in the adjoining Dracophyllum scrub. This formation is broken up by deep gullies through which flow small streams of water, and these are filled up with dense masses of Ligusticum latifolium, Lig. antipodum, and Stilbocarpa polaris.
Anatomy (fig. 7.).—There is a very thick and wrinkled cuticle (cut.) extending above the epidermis of the leaf. When stained with chlor-zinc-iodine it gives the distinctive yellow colour of cutin. The epidermis (ep.) consists of a single layer of thick-walled cells, more or less flattened. Stomata (st.) (fig. 8c) occur only on the lower epidermis (l.ep.). Below the epidermis comes a very strongly developed stereom (sm.), mixed with collenchyma tissue (col.), which gives a blue colour with chlor-zinc-iodine. On the upper surface this tissue may be 3—4 cells in thickness of rather large cells, and on the lower it is only 2 cells thick at most, and the cells are much smaller. At the edges the leaf stereom tissue is again found attaining a thickness in many cases of 0·33 mm., and it is the chief constituent of the tissue of the
[Footnote] * Kirk (1899), p. 200.
[Footnote] † Cockayne (1903), p. 262.
[Footnote] † Hooker (1864), p. 94.
acicular points at the ends of the lobes. The stereom is developed in groups consisting of cells with highly translucent cell-walls and very small lumina, represented in fig. 8b by small black strokes. This tissue has been developed to give rigidity to the leaves, to enable them to resist the fierce winds to which they are exposed, and to protect the delicate chlorophyll tissue below. In this way “it performs functions quite similar in many respects to those of the bony skeleton of higher animals.”* At intervals this strengthening tissue interrupts the chlorenchyma and occupies the whole width of the leaf surrounding the vascular bundle (see fig. 7). The chlorenchyma is differentiated into palisade and spongy tissue, and is more or less separated into strands by the stereom tissue, as mentioned above. The palisade tissue (pal.) is from 3—4 layers thick, and consists of rectangular cells about twice as long as broad, with the chlorophyll usually on the vertical or side walls. The spongy tissue (sp.) is composed of smaller rounder or oval-shaped cells, occupying twice the area that the palisade does, and leaving numerous air-spaces. Just above the lower epidermis come two layers of very much smaller cells densely filled with chlorophyll. The vascular bundles are found surrounded by the stereom tissue (sm.). The smaller veins are frequently imbedded in the palisade tissue with a surrounding mass of stereom. The canals (c.) common to this order above (Umbelliferœ) are found both above and below the larger veins. They are boardered by a layer of epithelial cells (b.), which are usually empty, but may contain granular protoplasm. Fig. 8b shows one of these canals enlarged.
Ligusticum antipodum, Hook. f., Fl. Antarc., i, 17, t. 9, 10.
“Blade oblong or broadly oblong, 2—3-pinnate, coriaceous, dissected into countless narrow, linear, subulate segments, ¼ in. broad, with acicular points.”† On the lower surface of each segment is a ridge corresponding with a depression on the upper surface, just above the midrib (see fig. 8a).
Hab.—Lord Auckland Islands and Campbell Island; marshy places.†
In Lord Auckland Group it occurs in the Pleurophyllum meadow with Lig. latifolium, “their stout rhizomes and huge rigid leaves stopping the progress of pedestrians.”§
In Campbell Island it is found with Lig. latifolium and Stilbocarpa polaris in the small streams running at the bottom of the
[Footnote] * Detmer Moor (1898), p. 518.
[Footnote] † Kirk (1899), p. 200.
[Footnote] † Hooker (1864), p. 94.
[Footnote] § Cockayne, p. 258.
gullies between the hills. It occurs again in the subalpine rock region. On the face of a precipitous rock facing northwest it grows in the chinks of the rock. Here it is very much smaller and has stiffer and more coriaceous leaves than when growing as a meadow plant. Then, it is found again on the wind-swept summit, and again on another rock “dripping with water and densely covered with mosses and liverworts.” Here the bases of the leaves are densely sheathed with old leaf-bases. “The leaves arch upwards and outwards radially, with the result that many of the stiff needle-like pinnæ are almost vertical and others horizontal. Each primary leaflet finally arches downwards. In a position such as this the conditions, although on a rock, are not very different from those of a bog, except that the water will be distinctly more pure.”* The drooping habit thus described seems characteristic of all the plants of Ligusticum antipodum I have seen.
On Antipodes Island the plant is also abundant; on the maritime tussock slopes where the tussocks are not so close together, and on the flat tussock meadow, it occurs in such quantity as to add bright-green patches of colour in an equal proportion with the yellow grass or dark fern. It plays an important part as a shelter plant, its leaves spreading out radially, with their surface more or less horizontal, such plants averaging about 78 cm. in diameter and 22 cm. in height. It is found again in the “bog”—patches of very wet soil in the meadow— and here it is very abundant, more so than in the adjacent meadow.
Anatomy (figs. 8a, 8b, 8c).—The leaf is roughly oval in transverse section, with a depression on the upper surface above the main vascular bundle, and a ridge corresponding to it on the lower surface. The cuticle (cut.) is strongly developed, being very thick and wrinkled. The upper epidermis (ep.) is composed of thick-walled cells, some with very small lumina and highly refractive thick cell-walls. Stomata (st.) occur on both surfaces, the opening or stoma being partially overlapped by the projections of the cuticle (fig. 8c). Below the epidermis comes a layer of stereom (sm.) tissue, sometimes only one cell in thickness, in other places several cells thick and extending right into the chlorophyll tissue towards the vascular bundles. This is also further strengthened with collenchyma (col.), which acts as water-storage tissue. The chlorenchyma (chlor.) is not differentiated into the ordinary palisade and spongy tissue, but consists of a homogeneous mass of small, somewhat oval-shaped cells arranged more densely on the outer portion of the tissue,
[Footnote] * Cockayne (1903), p. 282.
but stretching in chains across the central portion, leaving large air-spaces (a.s.). The vascular bundles (v.b.) are protected by stereom tissue (sr.), and are surrounded by an endodermis (endo.).
Stilbocarpa polaris, A. Gray.
“Leaves 6 in. to 12 in. broad or more, almost fleshy, bristly on both surfaces, orbicular-reniform, many - lobed, strongly toothed; veins flabellate, principal veins and smaller reticulations divide the leaf into distinctly marked areas made prominent by the depression of the veins; the bristles of the upper surface, which may be ½ in. or more in length, found in these areas; on the under surface they are found on the larger veins, and are more numerous.”*
“The large rhizome, measuring ±8 cm. by ±7 cm., creeps on the surface of the ground. Usually about six fully developed leaves are given off from an ascending portion of the stem. These leaves are ± 6 cm. broad at the sheathing base, which is furnished with a very large stipule ± 18 cm. long by 10 cm. wide at the apex, its widest part. Such stipules in part enclose the interior bud, against which they are pressed tightly by their concave inner surface, and play a most important part in its protection. The petiole, ± 54 cm. long, is thick, but hollow. The leaf-blade is orbicular-reniform. It is ± 19 cm. in length, measuring from sinus to apex, and ± 29 cm. broad. These leaf-blades are more or less in the form of a funnel, through the lobes of the reniform base being bent inwards, and so convey any water which falls on them to the roots of the plant. The leaves on both surfaces and the petioles are furnished with many pale hairs 10 mm. in length.”†
Hab.—This striking plant was described by Hooker (1847) as Aralia polaris, following the nomenclature of Hombron and Jacquinot.‡
Lord Auckland Group and Campbell Island : “In the woods and on banks generally near the sea, but often attaining an altitude of 600 ft. to 700 ft., covering large tracts of ground with its bright and shining green foliage.”§ “It occurs everywhere at low elevations on these islands, and is of a decidedly antarctic type, extending from Macquarie Island to Antipodes Islands.”∥
Auckland Islands: “In the Pleurophyllum meadow great
[Footnote] Kirk (1899), p. 215.
[Footnote] † Cockayne (1903), p.261.
[Footnote] ‡ Voy. au Pôle Sud.
[Footnote] § Hooker (1847), p. 19.
[Footnote] ∥ Kirk (1891), p. 221.
rounded leaves still from as dense masses of greenery as in summer.”*
Campbell Island: “It accompanies Ligusticum latifolium down to the stony beach, but not quite so near the water's edge” (p. 270). “In the Dracophyllum scrub it follows the many watercourses which cut into the hillside, and grows luxuriantly in the running water” (p. 273). “It is found in the deep gullies cut into the sides of the scrub formation” (p. 274)
Antipodes Islands: Inland tussock slopes. Frequently fern, tussock, and scrub give place to great masses of Stilbocarpa polaris, forming dense thickets. “One colony of this remarkable plant measured 11 m. by 3 m., but those met with further on, of which no measurements were taken, were of much larger size” (p. 292).
Anatomy figs. 9a, 9b).—The upper epidermal cells (ep.) are large, rectangular, and slightly cuticularised, while those of the lower epidermis are much smaller and have no cuticle. Stomata (st.) are found under the surface only. The hairs (h.h.) are solid multicellular bodies arising below the veins on the under surface, and in the areas between the veins on upper. Below the epidermis is usually a layer of colourless cells with thinner walls, probably water-storage tissue (st.l.). The chlorenchyma is differentiated into palisade (pal.) and spongy (sp.). The palisade (pal.) consists of four layers of small oval-shaped cells, closely packed together, and very regularly filled with chlorophyll. Below this comes the first portion of the spongy tissue, which consists of larger, more rectangular, and colourless parenchyma cells, arranged in chains. Then occurs a large air-chamber separating this last layer from the layer of very small rounded cells densely filled with chlorophyll. The two layers are united at certain parts of the leaf where the veins occur. The vascular bundle (v.b.) is surrounded by a thick-walled endodermis, and is strengthened on the under surface by a little mass of hypodermal stereom tissue, and also by a further mass of collenchyma. This tissue in some cases contains a certain amount of chlorophyll where it joins the endodermis. The epidermal cells (ep.) immediately below the veins are larger than ordinary, and oval, with projecting outer walls.
Coprosma cuneata, Hoof. f.
“Leaves yellowish-green when fresh, crowded, mostly fascicled on short arrested branches ⅕ in. to ⅔ in. long, 1/10 in. broad, linear or oblong-obovate, or obovate-lanceolate or cuneate-oblong, retuse subacute or obtuse, patent or recurved, very rigid,
[Footnote] * Cockayne (1903), p. 258.
coriaceous, often shining; midrib deeply sunk above, narrowed at the base, but scarcely petioled; stipules short, broad, fimbriate or ciliate.”*
Hab.—This woody plant forms one of the most constant constitutents of the scrub formations on the more exposed portions of the islands.
In Auckland Island it occurs on the peaty soil of the subalpine meadow, creeping close to the ground, and in that way obtaining shelter from the larger tussocks and more erect plants.
On Campbell Island it forms one of the ligneous members of the Dracophyllum scrub, the only approach on the island to a forest formation. It is here more luxuriant where it is sheltered from the wind, but still of a prostrate habit. It occurs also at higher elevations in the subalpine meadow and rock formations, still “prostrate” and “stunted.”
On Antipodes Island it is found amongst the scrub, on the tussock slopes, and again in the bog formation, creeping close to the ground; “its small leaves in winter are quite brown” (p. 295).
On the rockery this plant is not more than 1 ft. high, but its straggling habit is very evident, while its scraggy branches with their few scattered leaves would easily associate it with a bleak and wind-swept natural home. Its leaves are very small and wedge-shaped, and occur in greater numbers at the ends of the branches. Dr. Cockayne thus describes the bushes: “As for the Coprosmas, they consist within of dense masses of bare interlacing twiggy branches. On the periphery alone of such bushes is the actual green part of the plant, and this leafy zone only penetrates into the plant for a distance of 7 cm. at most” (p. 274).
Anatomy (fig. 10).—There is a very distinct and wrinkled cuticle (cut.) outside the epidermis on both surfaces of the leaf. The cells of the upper epidermis (ep.) are large, thick-walled, and frequently contain oil-globules (o.g.). There are no stomata on this surface. The lower epidermal cells are only about one-quarter the size, and they are interrupted frequently by stomata which are accompanied by subsidiary cells (see fig.). The chlorenchyma is differentiated into palisade (pal.) and spongy (sp.), but the chlorophyll is poorly developed; instead there are numerous oil-globules (o.g.) throughout this tissue of the leaf. The palisade (pal.) consists of 3–4 layers of cells about four times as long as broad, closely packed together, except at intervals where they appear to have small openings, probably aircanals (a.c.). These differ from any air-canals described in Ligusticum in that they are not surrounded by an epithelium,
[Footnote] * Kirk (1899), p. 244.
and do not bear any distinct relation to the vascular bundles, as those of Ligusticum appear to do. These in Coprosma are just intercellular spaces left in the palisade tissue. The spongy tissue (sp.) is made up of irregularly shaped cells with numerous small intercellular spaces between them. The vascular bundles (v.b.) are surrounded by an endodermal layer (endo.) of parenchymatous cells of varying thickness.
There are no pits on the leaves of this species, and no hypodermal water-storage layer, as described for other larger species by Miss Greensill (1902).
Coprosma repens, Hook. f., Fl. Antarc.
“A small glabrous creeping matted species. Bark grey. Branches from 1 in. to 2 ft. in length, sometimes flaccid, densely leafy. Leaves close-set, rarely distant or fascicled, suberect or spreading, 1/10 in. to ⅓ in. long, lmear-oblong or broadly oblong to linear or broadly obovate, rounded at the tips or subacute, narrowed into very short broad petioles, veinless, very coriaceous, margins thickened. Stipules broad, obtuse, usually glabrous.”*
In the leaves of the plant growing on the rockery a midrib was distinctly visible, and on examining a transverse section the presence of several smaller veins was revealed.
Hab.—This plant occurs on Auckland Island in the subalpine meadow, the soil of which is in some places so wet as to deserve the name of bog. Its stems here are described as fleshy.
On Campbell Island it occurs in a much bleaker situation on the subalpine tussock meadow, where there are colder winds and the frosts are longer and more severe than at a lower level. Here its growth is stunted. “Wind is here the determining factor as to whether grass or arborescent growth shall predominate” (p. 278).
On Antipodes Island, in the tussock meadows where there is a badly drained and poorly nourished soil, the Coprosma bushes are also stunted in their growth, and this where the soil is of a soft peaty nature, and so moist that “it can be quickly kneaded into the consistency of porridge.” In the bog formation, where “water can be readily wrung out of the surface soil,” Coprosma repens is again found.
The small plant growing on the rockery illustrates strikingly the peripheral position of the leaves. The bare stem, about 2 ft. in length, bends right over and almost buries its leafy terminal portion in the soil, so that I was for some time in danger of overlooking it altogether. Its anatomical structure presents
[Footnote] * Kirk (1899), p. 245.
some slight modifications on that of Cop. cuneata, but possesses in common with it a strongly wrinkled cuticle and numerous oil-globules throughout its tissue.
Anatomy (fig. 11).—There is a distinct and wrinkled cuticle (cut.) on both surfaces. The cells of the upper epidermis (ep.) are large, and contain numerous oil-globules (o.g.). Stomata (st.) are found only on the lower epidermis (l.ep.), the cells of which are much smaller than those of the upper. The chlorenchyma is differentiated into palisade (pal.)—two layers of large palisade cells, much larger than those of Cop. cuneata, and containing more chlorophyll; the spongy tissue (sp.) makes up the greater portion of the leaf, and is more loosely arranged than that of Cop. cuneata. Bundles of raphides (r.) are arranged in certain of its cells. There is a distinct endodermis (endo.) surrounding the vascular bundles (v.b.). All the tissues contain a considerable amount of small oil-globules (o.g.).
Olearia lyalli, Hook. f.
“Leaves broadly ovate or orbicular-ovate; abruptly acuminate; densely tomentose, newly formed leaves white above and below, the tomentum on the upper surfaces falling away in the first winter. Mature leaves very thick and coriaceous, doubly crenate with short sheathing petioles; on young specimens growing in the shade leaves are much thinner and very large.”*
“The under surface is densely clothed with flannelly tomentum quite white in colour. This tomentum is rather more than half the thickness of the leaf-substance proper. The young leaf just when it is unfolded from the bud is white and soft like a piece of flannel, being extremely tomentose on both surfaces.”†
Hab.—This tree is extremely local in its distribution. It is not found at all in New Zealand, but occurs only on the Snares, where it is the principal tree on the island. “On Ewing Island, and perhaps to a very limited extent on Auckland Island itself.”‡
Snares Island: This tree, by reason of its white-covered leaves, gives a peculiar grey or whitish hue to the foliage. Kirk describes its mode of growth as follows (1891, p. 215): “When growing in level situations it is erect, with open spreading branches; but when growing on slopes exposed to the wind it is often inclined or with a prostrate trunk, the roots partly torn
[Footnote] * Kirk (1891), p. 216.
[Footnote] † Cockayne (1903), p. 253.
[Footnote] ‡ Cockayne (1903), p. 252.
out of the soil, and the branches rooting at the tips give rise to new trunks, which in their turn are brought to the ground and repeat the process.”
Auckland Islands; Ewing Island: “Most of them are erect and well-grown, but a few exhibit the inclined position so frequent on the Snares.”* Dr. Cockayne considers that although this prostrate habit is frequently caused by the wind, it may become hereditary. The seedlings which were found in great quantities in the interior of the forest, where the air is comparatively still, were found by him to have their stems prostrate on the ground for more than half their length (p. 254). So in these cases the tendency had become hereditary.
There is a plant growing in the shade afforded by a high iron fence on the west side of the laboratory. This plant is quite erect, and shows the characteristic appearance of the leaves. In the older ones the tomentum has fallen off the upper surface, while the younger ones are completely covered and feel “soft as a piece of flannel.”
Anatomy (figs. 12a, 12b).—A cuticle (cut.) is developed on the upper epidermis, thick but smooth. The cells of the upper epidermis (ep.) are much larger than those of the lower (l.ep.), and very thick-walled, in some cases somewhat flattened. In the younger leaves these cells grow out to form a tomentum, also with thick walls. The remains of one or two of these hairs may be seen at h in the figure. These hairs fall away the first winter. The lower epidermis (l.ep.) is irregular in outline, and the small cells grow out into a thick mass of long woolly hairs (h.), chiefly below the veins. These completely protect the projecting stomata (st.). The hairs will serve the double purpose of protecting the stomata from the action of the winds, which tend to cause excessive transpiration, and also serve to retain any water which falls on the leaf. Amongst these hairs and also protected by them are found a number of multicellular bodies, probably glandular, the cells of which contain a small quantity of chlorophyll (fig. 12b). These can assist the plant by absorbing water held in the spaces between the hairs. The stomata (st.) project from the surface, and each guard-cell is accompanied by a subsidiary cell which probably aids in opening and closing the stoma. Underneath the upper epidermis is found a tissue from 2–3 cells thick of very large thick-walled cells, probably collenchymatous water-storage tissue (Pierce). The cells are quite empty, and at intervals above the vascular bundles interrupt the palisade parenchyma, and continue down the whole breadth of the section to the endodermis of the vascular bundle, in some cases pre-
[Footnote] * Kirk (1891), p. 219.
senting a scalariform appearance similar to the thickenings of the scalariform tracheides of ferns. The chlorenchyma is differentiated into palisade (pal.) of two layers and spongy (sp.) of three or four layers of cells. The palisade cells are very large in comparison with those of the spongy tissue, elongated at right angles to the surface, being about twice as long as broad, with few but large chlorophyll corpuscles. The spongy tissue consists of small irregularly shaped cells, sparingly filled with large corpuscles, and leaving comparatively few air-spaces. These border directly on the lower epidermis. The vascular bundles are found of varying size in a transverse section, but all are surrounded by an endodermis of round cells. The larger ones consist of a dark xylem and a light-coloured phloem, with a band of cells intermediate in colour between the two (fig. 12a). Underneath the larger bundles also is a ridge of tissue composed of more or less rounded and thick-walled cells. The cells of the epidermis adjoining them are larger than the other cells of the lower epidermis, and, as I mentioned before, considerably elongated into hair-like outgrowths.
Abrotanella rosulata, Hook. f.
“A small, densely tufted, moss-like plant. Leaves imbricating, patent or recurved, rigid, coriaceous, ¼ in. to ⅓ in. long, narrow, ovate or lanceolate, acute, concave above.”*
“It has wiry stems, creeping at first, but finally erect, covered more or less with old dead leaves. The terminal leafy portion of the shoots measures 1·3 cm., and consists of spreading imbricating leaves, the uppermost of which form a stiff, dark-green rosette about 1·3 cm. in diameter, the individual leaves so spreading outwards as to have their upper surface horizontal. The individual leaves are linear or linear-lanceolate, sheathing at the base, which is frequently purplish-rose-coloured, coriaceous, concave on the upper surface.”†
Hab.—Kirk mentions it in his account of the Campbell Island flora: “The endemic A. rosulata occurred sparingly on exposed rocks, but was not observed below 1,000 ft.”‡ Dr. Cockayne places it amongst the subalpine rock vegetation of Campbell Island, forming “stiff rosettes” on “the face of a precipitous rock facing north-west at an altitude of about 538 m.” (p. 282). It may be classed, therefore, as a rock-plant with Phyllachne clavigera, Colobanthus subulatus, and its relative, Abrotanella spathulata, and with them presents certain xerophytic characters in its anatomical structure.
[Footnote] * Hooker (1864).
[Footnote] † Cockayne (1903), p. 283.
[Footnote] ‡ Kirk (1891), p 223.
Anatomy (fig. 13).—There is first a very thick and wrinkled cuticle (cut.) on the upper surface. The epidermal (ep) cells are also thick-walled, and more or less cubical in shape. On the upper surface stomata (st.) are present, slightly sunken below the cuticle. On the lower surface, which is not exposed to the sun or wind, there is no cuticle, and the stomata appear on a level with the epidermal cells. At the most convex part of the leaf the epidermal tissue is strengthened by two or three layers of very thick-walled cells, which may represent stereom-supporting tissue. The chlorenchyma is differentiated into palisade (pal.) and spongy (sp.). The palisade consists of 3–4 layers of the ordinary palisade cells, somewhat small and very closely packed, and densely filled with chlorophyll. Below this comes the spongy tissue, first consisting of a mass of larger rounded cells occupying the centre of the leaf, and below these again come smaller rounded cells bordering on the lower epidermis, and densely filled with chlorophyll. The intermediate larger cells are somewhat scantily supplied with chlorophyll. The vascular bundles (v.b.) are regularly arranged in the leaf. In the lower part of the leaf we find five bundles; higher up the two have converged into three, and higher up still only one is found. Resin-passages regularly lined with epithelium are found, usually one above and one below each bundle.
Abrotanella spathulata, Hook. f.
“Leaves narrow, linear-spathulate, ½ in. to 1 in. long, obtuse or acute, rather close-set, spreading, foliaceous.”*
Hab.—“Auckland Islands, 1,000 ft. to 2,000 ft.; Campbell Island, 500 ft. to 800 ft.”†
I find that Dr. Cockayne has not given any account of this plant except to state, in the list of plants at the end of his paper, that it is found in Auckland and Campbell Islands. He also mentions it (p. 281) as belonging to the subalpine rock flora of Campbell Island. It belongs to the same class of rock-plants, and would be found in Auckland Island on the higher rocky ground. It is growing on the rockery side by side with A. rosulata. Its leaves are longer and the rosettes consequently larger than those of A. rosulata, and the purplish colour of the lower membranous portion of the leaf is absent in A. spathulata. Otherwise the appearance of the two is very similar, and an examination of the anatomy does not reveal any striking differences. There are more vascular bundles and consequently more resin-passages, but in other details the structure is very similar.
[Footnote] * Kirk (1899), p. 330.
[Footnote] † Kirk (1899), p. 331
Anatomy (fig. 14).—In a transverse section of a leaf of this plant were seen small pits or indentations on the upper surface, one of which is given in fig. 14a. These pits, or others very similar to them, are found on both surfaces of the two species of Cotula next described, but what their significance is I cannot say. They are not there for the protection of the stomata, for the stomata occur on the exposed epidermal surface. In this plant the bordering epidermal cells contained several small oil-globules, which were also found in other cells of epidermis. There is a thick, smooth cuticle (cut.) protecting the epidermis on the upper surface. The epidermal cells (ep.) are more or less cubical, except those forming the lining to the pits (a), which are somewhat elongated. Stomata (st.) are found on both surfaces. The chlorenchyma is differentiated into palisade of 4–5 layers of slightly elongated cells, somewhat larger than those of A. rosulata, and spongy tissue (sp.), consisting of rounded cells similar in size and position to those of A. rosulata. The vascular bundles (v.b.) are surrounded by a well-marked endoderm, while above and below each bundle is a resin-passage (c) lined with epithelium. Another resin-passage is found near each edge of the leaf, so in the sections figured in Plate XXXI there are eight resin-canals and three vascular bundles. Below the midrib is a layer two cells thick of hypodermal collenchyma (col.), while the epidermal cells themselves are also strengthened by collenchymatous tissue.
Cotula Ianata, Hook. f.
“Cotula lanata has pale-green or brown prostrate stems, which creep along the ground or hang down the face of vertical cliffs. The extremities of the stems are ascending, bending upwards and bringing into the light the terminal leaf rosettes, which consist of a few spreading pale-green pinnatifid leaves. The stems are marked at intervals with old leaf-scars, and from some of the nodes roots pass downwards into the rock-crevices, thus firmly anchoring the plant to the substratum. Leaves are fleshy and vary in colour, those innermost and not fully developed being of a darker green than the longer and more external ones. In shape they are obovate, the blades deeply pinnatifid, × 15 mm. long by ± 12 mm. broad, and the segments are toothed on the upper margins [see fig. 15b]. Such teeth, ± 2 mm. long, are bent at an angle, frequently almost at a right angle, to the plane of the leaf, thus making one-third of the assimilating surface vertical or nearly so, while the remaining two-thirds is horizontal. The fleshy, pale-coloured petiole is nearly twice as long as the lamina, and possesses a broad sheathing base ± 5 mm. long, furnished with a membranous margin. The petiole and
midrib are covered, especially in young leaves, with cottony hairs loosely interwoven. The leaves close to the end of the shoot are arranged spirally, but the remainder are brought into two ranks through twisting of the leaf-sheath, the leaf-surface thus becoming horizontal”* (cf. Epilobium confertifolium).
Hab.—This plant appears to flourish well near the sea, where it is frequently washed by the salt spray. In the Auckland Group it is found in certain cases trailing over the rocks on the shore just above high-water mark, and therefore “very frequently drenched by the sea-spray,” or rooted in the chinks of the vertical rocks with its long stems trailing down the face of the rock. It is also mentioned as occurring in the Pleurophyllum meadow with Cot. propinqua.
On Campbell Island it is found creeping over the stones of the rocky shore.
Plants inhabiting a maritime region are sometimes spoken of as salt-loving, but this name is a misnomer. Plants thus situated often flourish quite as well, if not better, in a soil free from salt; but in this way they escape competition with other plants which would certainly get the best of them in a richly cultivated soil. They have some particular adaptation which enables them to compete successfully with the adverse conditions which would kill other plants at once. So they flourish where they can, “but at the same time are always tacitly protesting against their environment, for they at once show how much more vigorous they can become when they are grown in a different and more congenial soil.”† So this Cotula lanata flourishes very well on the rockery right away from sea-spray, but its peculiar and characteristic structures by which it prepares itself to maintain an existence in its natural habitat remain, being hereditary.
The leaves are thick and fleshy, and little pits may be seen covering both surfaces. In the drawing illustrating a transverse section through the leaf the upper surface is more or less flattened, while the lower surface is concave.
Anatomy (figs. 15a, 15b, 15c, 15d).—Fig. 15a is a section through one of the teeth into which the upper margins of the leaflets are divided. The leaf is seen to be composed chiefly of a large-called thin-walled parenchyma (par.) containing few chlorophyll corpuscles, and leaving frequent air-spaces (a.s.), which occupy the centre of the leaf. This is bounded on each surface by a compact tissue, three cells or more in thickness,
[Footnote] * Cockayne (1903), p. 241–2.
[Footnote] † Henslow (1895), p. 34.
of small rounded cells with numerous chlorophyll corpuscles. This answers to the palisade tissue of other dorsi-ventral leaves, and is marked pal. These teeth are bent up at right angles, so that both sides are equally illuminated, hence the isolateral structure of the leaf. Another peculiarity is the presence of numerous pits or depressions, probably glandular, which are scattered over the leaf. These, as seen in fig. 15b, are walled in by epidermal cells much longer than the ordinary cubical ones, and at the base bounded by one or two smaller cubical cells. There is a thin cuticle (cut.) developed. The vascular bundle is surrounded by a well-marked endodermis (endo.), with walls considerably thickened. This is again surrounded by a layer of colourless parenchyma (p.s.) similar to the central water-storing tissue, the parenchyma sheath.
Cotula propinqua, Hook. f.
This plant differs from Cotula lanata in the appearance of the rosettes of leaves: they are much more open and spreading. Theleaves themselves are larger, as will be seen by comparing figs. 15d and 16b. The teeth into which the blade is divided do not overlap as in the case of Cot. lanata, and so the leaf appears flatter.
In the anatomical structure (figs. 16a, 16b, 16c) there are one or two points of difference. The cells of the palisade tissue (pal.) are larger in Cot. propinqua, and the corpuscles are also larger. The internal spongy tissue (sp.) is not so open, and the constituent cells are smaller, than in Cot. lanata. The stomata (st.) fig. 16c) are well developed; the guard-cells are kidney-shaped, and contain a very regular row of chlorophyll corpuscles, giving a beaded appearance.
Pleurophyllum speciosum, Hook. f., Fl. Antarc.
“Leaves all radical, 6 in. to 18 in. long, 5 in. to 10 in. broad, usually appressed to the ground, forming a huge rosette, broadly ovate or obovate or unequally rhomboid, rounded at the apex or shortly acuminate, thick when fresh, with 15–20 longitudinal ridges, loosely tomentose below, villous or setose above, the bristles being intermixed with rather long moniliform hairs.”*
Hab.—“Lord Auckland Group and Campbell Island; chiefly found upon wet banks and in marshes near the sea, but also ascending to the tops of mountains in a stunted form.”†
On the Auckland Islands Kirk (1891, p. 220) describes the plant as covering acres, giving a unique effect, approaching the
[Footnote] * Kirk (1899), p. 277.
[Footnote] † Hooker (1847), vol. i, p. 31.
magnificent. “As the traveller walks amongst them his feet crash through the horizontal leaves as though he were walking on thin ice.” On Campbell Island he notices that the plant here differs from that of the Auckland Islands: the leaves are larger, rather narrower, and more or less erect; they are invariably clothed with jointed or moniliform hairs mixed with straight tomentum, a character which is rare or absent from the Auckland Island form. “It is noteworthy that these differences, although of a trivial character, have proved constant under cultivation during ten years.”*
“In winter the huge leaves are altogether wanting and the rosettes are small and bright-green in colour, the leaves pressed closely against the ground. These rosettes vary considerably in size according to their position with regard to wind and light, those of shady gullies being much larger than those of the hillside.”†
On Campbell Island the plant is found where the ground is fairly wet, “its leaves larger and less decayed than in the meadow formation of Auckland Island” (p. 273). It is also found at higher levels in the tussock meadow, and still higher in the subalpine tussock, where the ground presents all the conditions necessary for a true bog formation.
The habit of the plant in forming these huge rosettes of leaves tightly pressed on the ground is of distinct advantage to it in resisting the severe winds which sweep over these open formations where the plant occurs. The leaves are so situated as to form a kind of cup in the centre. During rain this cup quickly fills with water, which soaks rapidly through the leaf-bases, bringing fresh rain-water to the roots. The leaves also become thoroughly wetted, their numerous hairs helping to hold the moisture, and it is probable that these also assist in the supply of pure water through their power of absorbing such, as suggested by Diels.‡
Anatomy (figs. 17a, 17b).—The plant growing on the rockery is not thriving very well, the rosette being very small, just 6 in. in diameter, and the largest leaves only 3 in. long. I did not venture, therefore, to injure it in any way by cutting at the leaves, and examined only a portion of the leaf in spirit. The chlorophyll is therefore undistinguishable. fig. 17a is taken through one of the prominent ribs on the under surface, and shows the position and structure of the vascular bundle (v.b.). fig. 17b is a section through the mesophyll tissue
[Footnote] * Kirk (1891), p. 224.
[Footnote] † Cockayne (1903), p. 258.
[Footnote] ‡ Cockayne (1903), p. 259
between two ribs, and shows the arrangement of this portion of the leaf. There is no cuticle, but numerous jointed hairs (h) are developed from the epidermal cells of both surfaces. The upper epidermis (ep.) consists of regular thin-walled rectangular cells, somewhat larger than those of the lower epidermis (l.ep.). Stomata (st.) are found only on the lower surface. Beneath the upper epidermis are arranged two rows of large colourless cells, acting as water-storage tissue (st.l.), and below these again come the chlorophyll-containing cells. They can hardly be said to be differentiated into palisade and spongy tissue. All the cells are of a fairly uniform size, being more or less cubical. Those just below the storage tissue are arranged compactly in two layers; the rest, about eight layers, are arranged more or less in chains, the ends of which adjoin the lower epidermis, thus leaving large air-spaces (a.s.) on the lower side of the leaf. The ribs of the leaf are made up of a mass of rounded collenchyma cells of varying size. On the lower surface the epidermal cells (l.ep.) are small in comparison, and thick-walled, giving rise to numerous hairs (h.), and just above this layer is another of larger cubical thin-walled parenchyma cells (par.). The vascular bundle (v.b.) is surrounded by a thick-walled endodermis (endo.). The xylem (xy.) is very strongly developed, while above it comes a tissue resembling the phloem (ph.) tissue below.
Senecio antipoda, Kirk.
“Branches spreading from base, very stout, grooved, ⅓ in. to ½ in. in diameter, fistulose, glabrous except peduncles and young leaves, mealy-tomentose beneath. Radical leaves apparently narrowed into a petiole; upper sessile by a broad auriculate base, membranous, sparingly and irregularly pinnatifid or partite, 2 in. to 5 in. long, 1 in. to 3 in. broad; segments toothed, lobed, or almost pinnatifid, acute.”*
“The upper surface of the leaf is green and almost glabrous in adult leaves, but the under surface is more or less tomentose with loose cobwebby hairs, the tomentum being much more abundant in young than in old leaves. The margins are recurved, and on the under surface of the leaf is a prominent midrib which gradually broadens towards the base. The tomentum plays an important part in protecting the bud in winter.”†
“Senecio antipoda much more resembles the common European groundsel in outward appearance than do any others of the herbaceous section of this genus in New Zealand” (p. 293).
[Footnote] * Kirk (1899).
[Footnote] † Cockayne (1903), p. 294.
Hab.—This interesting plant occurs only on Antipodes Island, and only in a certain part of that island. It is the dominant member of an association found on “the bare ground manured by the giant petrel (Ossifraga gigantea)” (p. 293). In this respect it resembles the endemic Cotula featherstonii of Chatham Island, which is found growing near the holes of the mutton-birds. With this Senecio are associated “very thick masses of Acœna frequently mixed with Pteris incisa.” With regard to this fact that we have an endemic species arising in two instances under similar conditions, Dr. Cockayne expresses himself thus: “I do not see why rich heavily manured soil should not be just as much a factor in determining the life-form of a plant as illumination, moisture in the air, wind, or any other ecological factor; and to find two plants each of distinctly luxuriant growth growing under very similar conditions is suggestive, to say the least” (p. 293).
Dr. Cockayne brought a plant from the islands and it was planted on the rockery, but it has since died, and shows no signs of sprouting again. There were only two or three green leaves left on the plant when I examined the rockery at the beginning of this year, and I was advised to examine them at once if I wished to do so at all, and therefore took the earliest opportunity of doing so before the plant died.
Anatomy (fig. 18).—This section includes the midrib, causing a marked prominence on the under side of the leaf and marked by a deep depression on the upper side. There is a very thin cuticle, if any at all, but the epidermal cells are provided with greatly thickened cell-walls. Those of the upper epidermis (ep.) are much larger than those of the lower. In the young leaf which was examined the woolly tomentum (h.h.) was present on the lower surface and protected the stomata (st.), which occur only on this surface in the areas between the veins. The guardcells contain several large chlorophyll corpuscles. The chlorenchyma is arranged as in any typical dorsi-ventral leaf. The palisade tissue (pal.) is two layers in thickness, composed of typical palisade cells with chlorophyll corpuscles arranged on the side walls. This passes into the open spongy tissue (sp.) which comprises the greater thickness of the leaf. A mass of thin-walled rounded parenchyma cells occupies the keel of the leaf, the larger cells near the main vascular bundle (v.b.) and smaller cells towards the epidermis, which here consists of a single layer of small thick-walled cells. In the phloem (ph.) of the bundle figured is a canal (c.) lined with epithelium (b.). The xylem (xy.) consists of rather large vessels arranged in chains.
Phyllachne clavigera (F. Muell.), Hook. f.
“Large green cushions, some of great size, the extremities of the shoots rooting in the decayed leaves now turned into peat, which make up the chief bulk of the cushions. Each main shoot branches near its extremity, giving off several short shoots 1·5 cm. in length, the upper 6 mm. of which are densely clothed with very small imbricating green leaves. These final shoots are all pressed tightly together, and make apparently a solid convex mass. The leaves are very thick, coriaceous, expanded at the base, convex on the under (outer) surface, but slightly concave on the lower half of the upper (inner) surface, but flat on its upper half. They are not quite erect, but the globose tips point slightly outwards.”*
This plant was described by Hooker (1847) as Forstera clavigera, Hook. f., but its claim to be included in the genus Phyllachne has since been established.
Hab.—“Lord Auckland Group and Campbell Island: on the mountains in turfy and boggy places; very common.”†
The semi-bog of the subalpine meadow of Auckland Island may be recognised “by the presence of the large, round, bright-green, dense cushions of Phyllachne clavigera.”‡
On Campbell Island it forms “large, bright-green, hard cushions” where the ground is wettest in the subalpine tussock meadow, and also among the subalpine rocks under similar conditions.
This plant is a “bog xerophyte of the typical form of many other antarctic cushion plants” (p. 265), which reaches its climax in the vegetable-sheep (Raoulia mammillaris) of New Zealand.
Anatomy (fig. 19).—This section is taken through the globose tip of a leaf, and is more or less hemispherical. The flatter surface represents the inner side of the leaf, and the convex the outer side. There is a distinct thick and wrinkled cuticle (cut.) surrounding the leaf. Underneath is the epidermic (ep.) of thick walls and rather large cells; stomata (st.) occur on any part of the epidermis. The chlorenchyma (chlor.) consists of a homogeneous mass of rounded cells, which occupy the entire section of the leaf. The outer portion is perhaps more densely filled with chlorophyll, and the cells are more closely packed, than in the central portion. Sometimes the cells appear to be arranged in chains, which, arising from the epidermal cells, converge towards the centre of the leaf where lies the vascular
[Footnote] * Cockayne (1903), p. 280.
[Footnote] † Hooker (1847), vol. i, p. 38.
[Footnote] ‡ Cockayne (1903), p. 265.
bundle (v.b.). The vascular bundle is surrounded more or less completely with a ring of large colourless parenchyma cells (par.).
Pratia arenaria, Hook. f.
In Hooker's Handbook this plant is described as Pratia angulata, var. arenaria.. The leaves are orbicular, sinuatetoothed, shortly petioled, and membranous.*
Hab.—“Lord Auckland Group: creeping over the open sandy shores of Enderby's Inlet, Rendezvous Harbour; Lieutenant H. Oakley.”†
This plant occurs associated with Epilobium confertifolium on the shady side of the gullies between the sand-dunes on Enderby Island.‡ It is also found in the tussock meadow of Antipodes Island.
Anatomy (fig. 20).—The leaf I examined was a young one, but could be easily identified as Pratia by the angular margin. The cells of the epidermis (ep.) were thin-walled, except beneath the vascular bundle, where the walls were considerably thickened (l.ep.). There was no cuticle developed, and stomata (st.) occurred on both surfaces. The chlorenchyma was differentiated into palisade (pal.) and spongy (sp.). The palisade tissue was just one cell in thickness, and the cells were the regular palisade form with chlorophyll corpuscles arranged on the side walls. The rest of the chlorenchyma is composed of spongy tissue (sp.), large thin-walled cells, not so densely filled with chlorophyll and not very loosely arranged. Underneath the vascular bundle is a mass of smaller-celled colourless tissue with thicker walls. The bundle (v.b.) is surrounded by a well-marked endodermis (endo.).
The spongy tissue will most probably act as water-storage tissue as well as the thicker-walled tissue beneath the bundle, a necessary modification for a maritime plant such as this.
Gentiana cerina, form v concinna, Kirk.
“Leaves very thick, coriaceous, obovate or spathulateoblong, ⅔ in. to 1½ in. long; radical and cauline similar, 3-nerved”; form v concinna, “long, coriaceous, obtuse, often recurved.” “A most beautiful plant; remarkable for the thick, trailing, leafy stems, bright-green, shining, succulent foliage.”§
[Footnote] * Hooker (1867), p. 172.
[Footnote] † Hooker (1847), vol. i, p. 41.
[Footnote] ‡ Cockayne (1903), p. 238.
[Footnote] § Hooker (1867), p. 191.
“In winter it has rather dense rosettes, crowded together, of dark-green imbricating leaves, the four or five outer leaves much larger than those crowded internally. In spring the rosettes open out, and the new branches spread out radially, with their tips ascending.”*
Hab.—“Lord Auckland Group: near the sea on rocky islets in Rendezvous Harbour.”†
In the Pleurophyllum meadow of Auckland Island “are grass-like tufs of Scirpus aucklandicu and the silvery-leaved Helichrysum prostratum, and very frequently associated with these are the shining green winter rosettes of Gentiana cerina.”‡
There are several rosettes of this plant on the rockery; it has grown and spread since it was planted there last year.
Anatomy (fig. 21).—The leaf I examined was very thick and coriaceous, with recurved margins. There is a more or less well-defined smooth cuticle (cut.) on the upper surface. The upper epidermal cells (ep.) are thick-walled, and slightly rectangular in shape. Those of the lower epidermis (l.ep.) are smaller, with thinner walls, no cuticle, but interrupted by numerous stomata (st.). The chlorenchyma is differentiated into palisade tissue (pal.)—consisting of oval cells in four layers and densely filled with chlorophyll—and spongy tissue, which makes up the greater thickness of the leaf, being about double that of the palisade. This tissue is loosely arranged, leaving numerous air-spaces (a.s.), and is not so densely filled with chlorophyll. The vascular bundle (v.b.) is surrounded by an endodermis (endo.) of colourless cells, surrounded by the larger chlorophyll containing cells of the mesophyll. The recurved margins of the leaf, together with the rosette formation, serve to protect the stomata on the under surface, and so check the rate of transpiration of the leaves.
Myosotis capitata, Hook. f.
“Leaves radical, linear, obovate or lanceolate, obtuse, 2 in. to 4 in. long, narrowed into broad petioles, hispid-pilose on both surfaces; cauline linear, oblong or spathulate, sessile.”§
“In winter it presents semi-rosettes of rather thick, soft, dark-green leaves, covered on the upper surface with bristly white hairs. The stems are prostrate, but with the extremities ascending and forming roundish tufts ± 16 cm. in diameter, and 6 cm. from the surface of the ground. The leaves are
[Footnote] * Cockayne (1903), p. 263.
[Footnote] † Hooker (1847), vol. i, p. 54.
[Footnote] ‡ Cockayne (1903), p. 259.
[Footnote] § Hooker (1864), p 194.
semipatent, and frequently recurved at their extremities, and dense enough for one rosette to touch the next.”†
Hab.—Auckland Island: “On gravelly banks near the margins of woods close to high-water mark.”*
In the Pleurophyllum meadow formation of Auckland Island (Cockayne).
Anatomy (figs. 22a 22b.)—There is no cuticle, but the epidermal cells (ep.) are protected by the very numerous hairs (h.h.) which are found thickly covering both surfaces, more especially the upper, which is most exposed. These hairs are unicellular outgrouwths of the epidermal cells. The upper epidermis (ep.) consists of regular rather thick-walled cells with no stomata; in the lower epidermis (l.ep.) the cells are smaller, thin-walled, and interrupted by very numerous stomata (st.). The chlorenchyma (chlor.) forms a regular palisade tissue (pal.), three cells in thickness, densely filled with chlorophyll. The spongy tissue (sp.) occupies the greater thickness of the leaf, and is composed of irregularly shaped cells, very loosely arranged, and so leaving numerous air-spaces. The vascular bundles (v.b.) are surrounded by the endodermis (endo.), and further by a colourless parenchyma sheath.
Veronica benthami, Hook. f.
“Leaves crowded towards ends of branches, sessile, ½ in. to 1 ½ in. long, linear or obovate-oblong, obtuse, margin with a few deep serrtures and edged with down, very coriaceous, flat, veinless; opposite pairs connate at the very base.”‡
“Leaves are thick, rather soft, narrow obovate-oblong in shape, dark-green; with regard to the light, the surfaces of the lower and larger leaves are horizontal and frequently arch downwards somewhat. The structure is that of a typical dorsi-ventral leaf. Nearer the apex of the shoot the leaves are smaller than those below, broader in proportion to their length, and loosely imbricating.”§
Hab.—“Small dwarf plant with deep glossy green foliage; near the sea.”∥
This plant is confined to the Auckland and Campbell Islands. On Campbell Island it is found growing through bushes of Coprosma or amongst the tussock, with its “rather straggling naked stems marked with many leaf-scars, but quite green above.”§ It appears again in the subalpine rock formation, in
[Footnote] † Cockayne (1903), p. 263.
[Footnote] * Hooker (1847), vol. i, p. 56.
[Footnote] ‡ Hooker (1867), p. 214.
[Footnote] § Cockayne (1903), p. 277.
[Footnote] ∥ Kirk (1891), p. 221.
[Footnote] § Cockayne (1903), p. 277.
those hollows between the rocks which afford plenty of shade and moisture and which are large enough for peat to have collected in abundance. In these same hollows occurs also the Ranunculus pinguis described above.
Anatomy (fig. 23).—There is a smoothe thickened cuticle (cut.) on both surfaces, interrupted on the lower side by numerous stomata (st.), which project slightly. The epidermal cells (ep.) are more or less cubical, with slightly thickened walls, the same size on both upper and lower surface. Just above the one vein is a depression on the upper surface, and this is lined by epidermal cells somewhat smaller than the rest, with slightly thicker cell-walls. The hairs (h.h.) forming the tomentum at the edges of the leaf arise in the epidermal cells: they are short and thin-walled. The chlorenchyma is differentiated into palisade (pal.) and spongy (sp.). The palisade tissue consists of a layer three cells thick of rectangular cells densely filled with chlorophyll. This passes gradually into the spongy tissue, composed of irregularly shaped cells with numerous air-spaces (a.s.), making up the greater part of the tissue of the leaf. There is only one vascular bundle (v.b.) in the centre of the leaf, which is situated beneath a depression on the upper surface. (This is probably what is meant by describing the leaf as “veinless.”) The bundle is surrounded by a well-marked endodermis (endo.).
There seems to be some doubt as to the real affinities of this species. It is found only on Ewing Island of the Lord Auckland Group, growing on the coastal rocks. Its leaves are arranged in rosettes. The upper portion of each leaf is toothed. In the small leaves I examined there were only two teeth, one on each side (fig. 24c). The lower portion is membranous and frequently coloured at the base with red colouring-matter. It grows with leaves flattened close to the rock. Dr. Cockayne states (p. 239) that this is the species referred to by Hooker (Fl. Antarc.) as P. carnosa, but that he afterwards classed it with the species P. brownii. In Dr. Cockayne's opinion, however, this plant bears “no resemblance whatever to the plant known as P. brownii in the Southern Alps. It much more resembles a species of Plantago very common in coastal situations in the neighbourhood of Foveaux Strait, which is probably P. hamiltonii, Kirk. The Auckland Island species certainly seems to me distinct from any New Zealand species” (p. 323).
There is a specimen of this plant growing on the rockery. The snow and frosts last winter destroyed most of the older and larger leaves, but it is now recovering and sending up a small rosette of green leaves through the old decayed ones,
while smaller rosettes are springing up all round. I have not been able to examine the plant with which it has been identified, but will merely give an account as fully as possible of its anatòmical structure.
Anatomy (figs. 24a, 24b, 24c).—A transverse section through the leaf shows a depression on the upper surface above the midrib, and a corresponding protuberance on the lower surface-Stereom (sm.) is developed in small amounts at the edges of the leaf and above the lower epidermis opposite the midrib. The cuticle (cut.) on the upper surface is smooth and thick, and the epidermal cells (ep.) of the upper surface have also greatly thickened walls. The lower epidermis (l.ep.) is made up of much thinner-walled and smaller cells. This surface of the leaf is very irregular. Peculiar hairs (h.) are developed on the surface. Each hair (fig. 24b) arises from an epidermal cell, and by division forms a stalk of two cells and an upper portion of elongated cells. These hairs are probably glandular. Stomata (st.) occur on both surfaces, but are most numerous on the lower surface. The chlorenchyma (chlor.) consists of a palisade tissue (pal.) composed of 5–6 layers of large oval-shaped cells with chloroplasts along the side walls, and a spongy tissue (sp.) closely arranged and consisting of only 3–4 layers. The cells are rounded, and contain few chlorophyll corpuscles. There is a definite and thick-walled endodermis (endo.) surrounding the vascular bundle (v.b.). There is a strong and unusual development of palisade tissue, which is a modification to intercept heat and light rays.
Astelia linearis, var. subulata.
“Growing in patches, the short stiff vertical green portions of the leaf rising above the ground for about 11 mm. This plant spreads into large colonies by means of its long wiry stems, which creep just beneath the surface of the ground. These stems are covered thickly with old decayed leaf-sheaths, and with these and the roots from extremely dense mats 3 cm. or more in length…. Just before issuing from the ground the stem branches into two or three leafy shoots, each furnished with 2–3 green leaves. Such leafy shoots, being quite close, form a rather dense turf. The leaves are ± 2·1 cm. long, and consist of a pale-coloured sheathing base, which is rather longer than the vertical or semi-vertical shining green subulate lamina. There are a few hairs on the sheath, and occasionally at the base of the lamina, otherwise the green portion of the leaf is quite glabrous.”*
[Footnote] * Cockayne (1903), p. 266.
This plant, as Dr. Cockayne points out, differs very considerably from the type, Astelia linearis, which Hooker (1867) describes as follows: “Leaves spreading, 1 in. to 6 in. long, narrow, linear, acuminate, keeled, margins recurved, silky and villous at the base” (p. 284); and Dr. Cockayne further adds, “that midrib and edge of leaf are covered with adpressed brown chaffy hairs” (p. 266).
Hab.—It occurs on both Auckland and Campbell Islands, in semi-bog formations.
Anatomy (figs. 25a, 25b).—The leaves are linear, glabrous, solid and cylindrical for the greater part of their length, but split down near the base along the line of colourless parenchyma cells. Fig. 25a is a section through the upper solid portion, while fig. 25b, which is much larger in proportion, is through the lower crescent-shaped portion of the leaf. The colourless parenchyma is on the upper surface; the leaves are here represented upside down.
Fig. 25a: A cuticle (cut.) may be distinguished above the epidermal cells, frequently interrupted by stomata (st.). The epidermal cells are more or less rounded or cubical in shape. The chlorenchyma (chlor.) is not differentiated, but consists of a mass of rounded cells densely filled with chlorophyll except on the upper surface of the leaf, where it is interrupted by a wedge-shaped mass of colourless thin-walled parenchyma cells. which probably acts as water-storage tissue. The number of vascular bundles (v.b.) varies. There may be one, two, or three at different heights in the leaf. The bundle is surrounded by a well-defined endodermis (endo.).
Fig. 25b differs in the position of the colourless parenchyma tissue (par.), which here forms a layer two cells in thickness along the greater part of the upper concave surface of the leaf. There are always three bundles in this region. In both cases raphides are present in certain of the chlorophyll-bearing cells, and anthocyanin is sometimes found in the epidermal cells.
Luzula crinita, Hook. f.
“Leaves flat and grass-like, with long white hairs on the margins and sheaths towards the base, 1½ in. to ⅙ in. broad.”*
Hab.—“Lord Auckland Group and Campbell Island: in the former locality it is found only near the tops of the hills, at an altitude of 1,200 ft.; more abundant in the latter, from the sea to an altitude of 1,200 ft.”†
It is found on most of the Southern Islands—Lord Auckland
[Footnote] * Hooker (1867), p. 293.
[Footnote] † Hooker (1847), vol. i, p. 84.
Group, Campbell Island, Antipodes Island, and Macquarie Island. It occurs at the higher eleyations, away from the sea and amongst the tussock formations.
Anatomy (fig. 26).—There is a very thick cuticle (cut.) on both upper and lower epidermis (ep.). The cells on the upper surface are very large indeed, their longer axes being at right angles to the surface of the leaf and their transverse walls thin; these cells are equal to any four of the cells of the palisade parenchyma. The cells of the lower epidermis are much smaller and cubical. It is on this surface that the stomata (st.) occur in rows between the veins. There are also present multicelluar hairs (h.h.) attached to the stereom tissue at the edge of the leaf. Stereom tissue occurs at the edges of the leaf, here consisting of cells with thick brown walls. It is also found on the upper and lower surface of each vascular bundle, partially enclosing them. The chlorenchyma (chlor.) consists of an undifferentiated mass of small rounded cells arranged along the epidermis and round the vascular bundles, but leaving numerous large air-spaces in the centre of the leaf. The vascular bundles (v.b.) occur at different intervals in the chlorenchyma tissue protected by a mass of stereom tissue. There is no well-defined endodermis present. The stereom tissue is developed to give mechanical support to the more delicate tissues against the action of the wind, and the large-celled epidermis acts as water-storage tissue
Scirpus aucklandicus (Hook. f.), Boeck.
This little plant is very widely distributed in the Southern Islands. It forms small soft green tufts measuring about 2 in., and is found growing in the crevices of the coastal rocks on Auckland Island where there is plenty of moisture. It is found in a similar position in Antipodes Island, here forming a dense mass which occupies an area of 1·35 m. by 60 cm., and measuring about 15 cm. deep.
The culms are a light-brown, and membranous, while the leaves arise in tufts (fig. 27b). They are roughly oval in outline in transverse section.
Anatomy (figs. 27a, 27b).—There is a thick-walled epidermis (ep.) of rounded cells surrounding the leaf, interrupted at regular intervals by small mass of stereom tissue (sm.) and numerous stomata (st.). The chlorenchyma (chlor.) is undifferentiated, and consists of a mass of small rounded cells in which are imbedded three vascular bundles (v.b.). Two large air-cavities (a.c.) occur in the central tissue, separated by a band of chlorenchyma only one or two cells thick. These air-cavities are a special modification frequently met with in swampy regions where the soil is not sufficiently aerated.
Carex trifida, Cav.
A very large tall robust leafy sedge, 3 ft. to 6 ft. high; culms stout, obtusely 3–9-onous, leafy, smooth. Leaves very large and long, ½ in. broad or more, flat, keeled, striate; margins scabrid. Is much the largest New Zealand species.*
Hab.—This plant is common in New Zealand and in all the Southern Islands except Macquarie and Bounty Islands. In the islands it is a common constituent of swampy ground, taking the place of the tussock-grass. It grows in immense tussocks. The leaf is conduplicate, with a prominent keel on the outer surface.
Anatomy (fig. 28).—The upper epidermis (ep.) is composed of large cells with cuticularized outer walls, slightly convex. The cells of the lower epidermis (l.ep.) are small, but still thick-walled, and interrupted by numerous stomata (st.). Masses of stereom tissue (sm.) occur above the smaller vascular bundles, and below the main one situated in the keel of the leaf. Above this main bundle is a mass of large-celled parenchyma, a single layer of which extends below on either side the upper epidermis to the first vascular bundle. The chlorenchyma (chlor.) is not differentiated, but consists of a mass of small rounded cells arranged in two layers adjoining each epidermis, leaving between large air-cavities which are separated by strands of tissue surrounding the vascular bundles. Each bundle (v.b.) is surrounded by a more or less well-defined endodermis (endo.). It occurs near the lower surface of the leaf, and the space between it and the upper epidermis is filled up with a mass of round thick-walled stereom tissue.
Poa foliosa, Hook. f. Festuca foliosa, Fl. N.Z., i, 308.
“Culms stout, tufted, tall or short, 1 ft. to 3 ft. high. Leaves flat, glabrous, coriaceous, shorter or longer than culms, 1½ in. to ¼ in. broad; ligule short, membranous, sheaths compressed.”
Hab.—This is found on all the islands, excepting of course the Bounty Islands, on which no vegetation occurs except a species of Durvillæa attached to the rocks, and on the rocks a species of alga. It forms broad zones of tussock in the different formations, and frequently attains a considerable size.
Anatomy (figs. 29a, 29b, 29c).—The leaf is hinged, and folds over on the central ridge at a, a. The ordinary upper epidermal cells (ep.) are rectangular, with the long axis vertical to the surface, and the outer wall projects into small papillæ with thickened outer walls (cf. Acœna). (See fig. 29b.) The epidemal
[Footnote] * Hooker (1867), p. 316.
cells occurring at the hinges a, a, are very large, with the long axis vertical to the surface, some wedge-shaped; their outer walls are just slightly convex. Above the masses of stereom tissue which occur at regular intervals on the upper surface the epidermal cells are much smaller and flattened, and the walls also do not project. It is on this upper surface, which is also the inner surface when the leaf folds over, that the stomata (st.) occur, partially protected by the papilleae. Each guard-cell is accompanied by a subsidiary cell (sb.), which assists in opening and closing the stoma (fig. 29b). The lower epidermis is composed of very thick-walled cells, with cuticularized walls, generally cubical in shape, those beneath the masses of the stereom tissue being much smaller, but still cubical. Stereom (sm.) occurs in various parts of the leaf as strengthening tissue against the effects of the wind. It is found above and below each vascular bundle (v.b.). It forms the little ridge projecting above the main vascular bundle on the upper or inner side of the leaf (sm1), and also a larger mass of it forms the keel-like projection on the lower surface (sm).
At a and a on either side of the central mass of tissue the tissue between the large upper epidermal cells, which probably act as hinges, and the lower epidermal cells is made up of a mass of thick-walled colourless cells (col.). The rest of the leaf consists of chlorenchyma (chlor.), small rounded cells densely filled with protoplasm. A well-defined very thick-walled endodermis surrounds each vascular bundle (fig. 29c). The xylem (xy.) of the bundle shows well-developed and thick-walled xylem vessels on the upper surface.
List of Literature Consulted.
1847. Hooker, Sir J. D.: “Flora Antarctica,” vols. l and in London.
1852. Hombron and Jacquinot: “Voyage au Pôle Sud: Botanique.” Paris.
1867. Hooker, Sir J. D.: “Handbook of the New Zealand Flora.” London.
1881. Kirk, T.: “Notes on Plants from Campbell Islands.” Trans. N.Z. Inst., vol. xiv, p. 387.
1883. Scott, J. H.: “Macquarie Islands.” Trans. N.Z. Inst., vol. xv, p. 484.
1884. Buchanan, J.: “Campbell Island and its Flora.” Trans. N.Z. Inst., vol. xvi, p. 398.
1891. Chapman, F. R.: “The Outlying Islands south of New Zealand.” Trans. N.Z. Inst., vol. xxxiii, p. 491.
1891. Kirk, T.: “On the Botany of the Antarctic Islands.”
Report Third Meeting, Austral. Assoc. for Advanc. of Science, p. 253. (This is the paper referred to in the essay as “1891.”)
1891. Kirk, T.: “The Botany of the Snares.” N.Z. Journ. of Science, new issue, p. 161, July.
1891. Kirk, T.: “On the Botany of the Snares.” Trans. N.Z. Inst., vol. xxiii, p. 426.
1891. Kirk, T.: “On the Botany of Antipodes Island.” Trans. N.Z. Inst., vol. xxiii, p. 436.
1895. Hamilton, A.: “Notes on a Visit to Macquarie Island.” Trans. N.Z. Inst., vol. xxvii, p. 559.
1895. Henslow, Rev. Geo.: “Origin of Plant Structures.”
1895. Kerner and Olliver: “Natural History of Plants.”
1898. Detmer: “Practical Plant Physiology.” Translated by S. A. Moor.
1898. Strasburger, &c.: “Text-book of Botany.” Translated by H. C. Porter, Ph.D.
1899. Kirk, T.: “The Students' Flora of New Zealand and the Outlying Islands.” Wellington.
1900. Kearney, Thos., jun.: “The Plant Covering of Ocracoke Island.” Contrib. from U.S. National Herbarium, vol. v, No. 5, August 1.
1901. Kearney, Thos., jun.: “Botanical Survey of Dismal Swamp Region.” Contrib. from U.S. National Herbarium, vol. v, No. 6, Nov.
1902. Greensill, N. A. R.: “Structure of Leaf of certain Species of Coprosma.” Trans. N.Z. Inst., vol. xxxv, p. 342.
1903. Pierce, G.: “A Physiology of Plants.”
1903. Cockayne, L.: “Botanical Excursion during Midwinter to the Southern Islands of New Zealand.” Trans. N.Z. Inst., vol. xxxvi, p. 226.
1903. Schimper: “Plant Geography.” Translated by W. R. Fisher.
List of Plants Examined, Arranged in Their Orders.
Ranunculus pinguis, Hook. f.
" subscaposus, Hook. f.
" aucklandicus, A. Gray.
Colobanthus subulatus, Hook. f.
Acœna sanguisorbæ, var. antarctica, Cockayne.
Epilobium confertifolium, Hook. f.
Ligusticum latifolium, Hook. f.
" antipodum, Hook. f.
Stilbocarpa polaris, A. Grav.
Coprosma cuneata, Hook. f.
" repens, Hook. f.
Olearia lyallii, Hook. f.
Abrotanella rosulata, Hook. f.
" spathulata, Hook. f.
Cotula lanata, Hook. f.
" propinqua, Hook. f.
Pleurophyllum speciosum, Hook. f.
Senecio antipoda, Kirk.
Phyllachne clavigera (f. Mueller), Hook. f.
Pratia arenaria, Hook. f.
Gentiana cerina, var. concinna, Kirk.
Myosotis capitata, Hook. f.
Veronica benthami, Hook. f.
Plantago sp. (brownii ?).
Astelia linearis subulata.
Luzula crinita, Hook. f.
Scirpus aucklandicus (Hook. f.), Boeck.
Carex trifida, Cav.
Poa foliosa, Hook. f.
Explanation of Plates XXVIII to XXXVII.
fig. 1a. Transverse section of leaf of Ranunculus pinguis; × 44.
fig. 1b. Transverse section showing stoma (st.) and guard-cells (g.c.).
fig. 2a. Transverse section of leaf of Ran. subscaposus; × 44.
fig. 2b. Surface section of epidermis; × 44.
fig. 2c. Leaf of same.
fig. 3. Transverse section of leaf of Ran. aucklandicus; × 44.
fig. 4a Transverse section of Colobanthus subulatus; × 44.
fig. 4b. Plant of same; half natural size.
fig. 5a. Leaf of Acœna sanguisorbœ antarctica.
fig. 5b. Leaf of var. pilosa; half natural size.
fig. 5c. Transverse section, leaf of Acœna sanguisorbæ antarctica; × 44.
fig. 5d. Transverse section, leaf of Acœna sanguisorbœ pilosa; × 44.
fig. 5e Transverse section through lower epidermis of a; × 65.
fig. 6a. Transverse section of Epilobium confertifolium; × 23.
fig. 6b. Shoot of same.
fig. 7. Transverse section, leaf of Ligusticum latifolium; × 23.
fig. 8a. Transverse section, leaf of Ligusticum antipodum; × 23.
fig. 8b. Section through resin-canal (c.); × 65.
fig. 8c. Section through a stoma; × 65.
fig. 9a. Transverse section, leaf of Stilbocarpa polaris; × 15.
fig. 9b. Section showing hair; × 15.
fig. 10. Transverse section, leaf of Coprosma cuneata; × 23.
fig. 11. Transverse section, leaf of Coprosma repens; × 23.
fig. 12a. Transverse section, leaf of Olearia lyallii; × 23.
fig. 12b. Transverse section, showing hairs; g.h., glandular hair; × 65.
fig. 13. Transverse section, leaf of Abrotanella rosulata; × 44.
fig. 14. Transverse section, leaf of Abrotanella spathulata; × 44.
fig. 15a. Transverse section, leaf of Cotula lanata; × 44.
fig. 15b. Section through pit; × 65.
fig. 15c. Section through vascular bundle to show endodermis; × 65.
fig. 15d. Leaf of Cot. lanata; half natural size.
fig. 16a. Transverse section, leaf of Cotula propinqua; × 44.
fig. 16b. Leaf of same; half natural size.
fig. 16c. Section through stoma; × 65.
fig. 17a. Transverse section, leaf of Pleurophyllum speciosum, through rib; × 15.
fig. 17b. Transverse section, leaf of Pleurophyllum speciosum, through mesophyll; × 15.
fig. 18. Transverse section, leaf of Senecio antipoda; × 15.
fig. 19. Transverse section, leaf of Phyllachne clavigera; × 44.
fig. 20. Transverse section, leaf of Pratia arenaria; × 44.
fig. 21. Transverse section, leaf of Gentiana cerima; × 44.
fig. 22a. Transverse section, leaf of Myosotis capitata; × 23.
fig. 22b. Surface section of upper epidermis (ep.), showing hairs (h.); × 23.
fig. 22c. Surface section of lower epidermis (l.ep.), showing stomata (st.); × 44.
fig. 23. Transverse section, Veronica benthami; × 44.
fig. 24a. Transverse section, Plantago; × 44.
fig. 24b. Surface view of epidermis, showing stomata and hair; × 44.
fig. 24c. Leaf of same; half natural size.
fig. 25a. Transverse section, leaf Astelia; × 44.
fig. 25b. Transverse section, leaf Astelia.
fig. 25c. Epidermis of Astelia; × 125.
fig. 26. Transverse section, leaf of Luzula crinita; × 44.
fig. 27a. Transverse section, leaf of Scirpus aucklandicus; × 44.
fig. 27b. Plant of same; half natural size.
fig. 28 Transverse section, leaf of Carex trifida; × 44.
fig. 29a. Transverse section, leaf of Poa foliosa; × 44.
fig. 29b Transverse section, showing stomata and papillæ; × 125.
fig. 29c. Transverse section through bundle, showing endodermis and vessels: × 215.
Lettering Used in Figures
ep Upper epidermis
l.ep. Lower epidermis
sb Subsidiary cell
st.l. Water-storage layer
pal. Pahsade tissue
sp Spongy tissue
a.s. Intercellular air-space
sm. Stereom tissue
cr. Crystal of oxalate of lime.
b. Epithelial tissue lining canal.
par. Colourless parenchyma tissue.
p.s. Parenchyma sheath.
v.b. Vascular bundle.