Art. XXVIII.—An Inquiry into the Seedling Forms of New Zealand Phanerogams and their Development.
[Read before the Philosophical Institute of Canterbury, 7th November, 1900.]
No. 360. Pittosporum rigidum, Hook, f. Plate X., figs. 1, 2, 3. (Continued from Trans. N.Z. Inst., vol. xxxi., p. 362.)
In the paper quoted above the seedling form of this species of Pittosporum is described as far as the development of the 5th leaf from seedlings which germinated early in the spring of 1898, and which are consequently now—28th August, 1900—about two years old. Some of the young plants are still growing in the flower-pot in which the seed was sown, and have been kept since their germination in an unheated gree-house. Others were transferred into separate pots some six months ago, since which time they have been kept plunged in moist sand in the shade-house, a structure consisting of a wooden frame-work, span-roofed, and covered with whitecalico blinds. Within this shade-house the air is usually more moist, the illumination much more feeble, the changes of temperature less extreme, and the wind less felt than in the open—indeed, the œcological conditions cannot be very different from those of certain forests, where the foliage is not extremely dense. The greenhouse as compared with the shade-house is hotter, moister, much more brightly illuminated, and its atmosphere is quite still. With regard to the plants in question, those of the greenhouse and those of the shade-house exhibit no differences of any moment. Most have produced one or two lateral shoots, which are given off from the stem at about an angle of 45°. The tallest plants are 9 cm. in height. Their stems are covered with numer-
[Footnote] * For Part III. see Trans. N.Z. Inst., vol. xxxii., art. xvi.
ous white hairs pressed close to the surface, and through which the very dark-purple bark can be seen. Those internodes nearest to the central portion of the stem are about 4 mm. in length, while those more adjacent to the apex are of greater length. Although the majority of the leaves do not vary to any great extent from those previously described as “deeply toothed or pinnatifid,” and figured in pl. xxx., fig. 4, of the above-mentioned paper, yet some few show considerable reduction of form. Such (fig. 1) are quite entire except for a few obscure marginal teeth, and approximate closely to the typical adult form of leaf. One exceptional seedling has nearly all its leaves of this latter type. Between the broad pinnatifid leaves (fig. 2) and the narrow almost entire leaves intermediate forms occur, whose laminæ are 11 mm. in length, 4 mm. broad for their basal half, and 1.10 mm. broad for the apical half. Such a leaf resembles a juvenile leaf in its lower and an adult leaf in its upper half. On page 363, l.c., I pointed out some of the differences between the early seedling and the adult leaves, at the same time suggesting that the reduction, &c., of the latter had been caused by the direct action of the environment on the plant in a state of nature. During a recent botanical excursion in the Waimakariri district I made some observations which seem directly confirmatory of the above-mentioned suggestion. The following extract from my note-book describes a particular example, and was written at the place of observation, a small patch of “bush” and its immediate environs on the right-hand bank of the River Waimakariri, just opposite the mouth of its tributary the River Hawdon, and where the eastern and western climatic regions* merge into one another “Pittosporum rigidum.—Seedlings of this are most plentiful under the beech-trees. They seem very similar to those raised artificially. Under the shade of the beech-trees the adult plants are of a loose habit, with erect twiggy branches scarcely interlacing, but in the open, only a few metres away, the whole plant forms a hard mass of rigid divaricating branches so closely interwoven that when one branch is pulled downwards the whole shrub is moved.” From the above we see that within the shelter of the forest, with its accompanying conditions of more equable temperature, moister atmosphere, much less bright illumination, rather wetter ground, and, above all, comparative freedom from wind, the adult plant is to all intents and purposes of the juvenile form, and so distinct in appearance from the plant growing under xerophytic conditions in the open that it could easily be mis-
[Footnote] * Cockayne, “A Sketch of the Plant Geography of the Waimakariri River Basin” (Trans. N.Z. Inst., vol. xxxii., 1899, pp. 117 and 131).
taken for a distinct species; and yet the individual of the forest and the one of the open might have been actually produced from seed not only from the same parent, but even from the same capsule. It is very difficult to estimate what part is here played by environment and what by heredity; at any rate, it seems to me that so long as the forest should present the same conditions, then so long would P. rigidum keep the juvenile form. And, further, were the xerophytic conditions absent, which state of affairs a change in climate could bring about, then the xerophilous form—i.e., the common form of the plant—would cease to be produced, though there seems no doubt that this form is hereditary, and thus the juvenile form, resembling most likely in many respects the ancestral form of the plant, be the sole survivor. On the other hand, a change of climate might banish the forests, and allow only the xerophilous form to exist.*
No. 783. Stellaria roughii, Hook. f. Plate X., fig. 4.
The seed was collected on the 3rd April, 1899, from one individual growing on a shingle-slip on the Mount Torlesse Range, at an altitude of 1,000 m. It was sown on the 9th September, 1899, and began to germinate on the 11th November, 1899, the germination continuing at intervals until June, 1900.
Description of Seedling.
Root very long and of very rapid growth; in a plant with the hypocotyl just visible above the soil it is 10.5 mm. long, and in a plant 5.5 mm. tall it is 31 mm. long; soft and succulent at first, but soon becoming extremely flexible; pale in colour, slightly wavy.
Hypocotyl greenish even when underground, afterwards pale-green, sometimes marked with brown on its upper portion; 4 mm. long before the cotyledons have emerged from the soil, finally 6 mm. in height above the soil; soft and succulent at first, but soon becoming so elastic that when bent to the ground it springs back into position; rarely quite straight and erect, often semiprostrate, terete, glabrous.
Cotyledons continue increasing in size for some time after they have opened out to the light, greenish even when under-ground, becoming finally pale-green; when fully grown 7 mm. (including petiole) in length by 1.5 mm. in breadth, linear-spathulate, obtuse or rarely subacute, entire, glabrous; petioles equalling lamina in length, semiterete, swollen and connate at the base.
[Footnote] * This idea is worked out at greater length further on in this paper when treating of the differences between Chatham Island seedlings and those of the same species in New Zealand.
Leaves opposite, rather succulent, in early stage of development vertical, with concave upper surfaces pressed tightly together, thus affording great protection to the growing-point of the epicotyl. As development proceeds the laminæ open out gradually and become horizontal, while at the same time the petioles increase very considerably in length.
1st pair of leaves (fig. 4)—in plant 15 mm. tall—oblong-spathulate, glabrous, entire, rounded at apex, of rather glaucous green; laminæ 3 mm. × 2.75 mm., tapering into the petiole; petioles almost equal in length to lamina, 1 mm. in breadth, flat on upper surface, rounded on under-surface, which is more or less deeply stained with purple, sheathing just above their swollen connate purple bases.
2nd pair of leaves similar in most respects to 1st pair, but paler in colour and stained with purple near base; laminæ almost rotund, petioles two-thirds the length of lamina, and midrib more evident than in 1st pair.
Stem very juicy, slender, and very elastic, quite glabrous, pale yellowish-green stained with purple; 1st internode 4 mm. long, 2nd internode 2.5 mm. long.
The adult form of Stellaria roughii has sessile, linear, succulent leaves, with an acuminate apex, and of an average size of about 17 mm. × 3 mm. These are indeed very different in shape from the long-stalked leaves of the seedling, with their almost orbicular blades. The adult plant grows in nature on “shingle-slips,”* which are often so unstable that when one moves the stones so as to take up a plant carefully the débris from above fills up the hole almost as fast as it is being made. Of soil strictly speaking there is little or none, and that little, when present, is merely coarse sand with a modicum of particles of clay. At a varying distance below the shingle, depending in large measure on the length of time which must have elapsed since the melting of the winter's snow, is a considerable amount of moisture. The seed from the plant, which is most likely a biennial, will fall under the shelter of its leaves. Here the young plants will be protected from excessive sunshine and wind, and, aided by a rapid root-growth, will soon be able to acquire the all-important water-supply. A transverse section of a seedling leaf shows that it is not ill provided even at an early age to resist excessive transpiration. There is a compact palisade and a rather close spongy parenchyma. On the under-surface the epidermis is 2-layered, the cell contents of the inner layer are often stained red, and on both surfaces is a well developed cuticle. The petiolate rotund juvenile leaves, and the sessile linear adult leaves, suggest comparison with the often-quoted example originally described by Goebel
[Footnote] * Cookayne, l.c., pp. 129, 130.
of Campanula rotundifolia, with its stalked cordate shade leaves, which are at the same time hereditary, and its sessile lanceolate leaves, which are an adaptation to excess of light; and it may well be that the sessile linear leaves of our plant are due to the strong illumination it must often experience in its exposed station.
The elastic stem, pale glaucous-green leaves, and early succulence of the seedling show how hereditary are some of the most striking peculiarities of shingle-slip plants. The colour of the leaves, for instance, is the forerunner of that curious grey colour, almost identical with that of the shingle, which nearly all the true shingle-slip plants possess.
When the cultivated seedlings have had the growing-point of the stem removed there has always been a rapid response in the growth of shoots from the axils of the cotyledons. This in a state of nature would be of great benefit to the plant; and damage to the growing-point, to which I should imagine wild seedlings are very liable, would be distinctly an assistance rather than a harm to the plant, by encouraging spreading growth.
Nos. 813 and 966. Gaya lyallii, Baker, var. ribifolia, *
The seed of No. 813 was collected near the foot of Mount Torlesse on the 31st March, 1899, at an altitude of 730 m., and that of No. 966 in the Trelissick Basin, at about the same altitude, towards the end of April, 1900. I possess no exact details as to the sowing and germination of No. 813. A part of the seed germinated in the spring of 1899; a few more plants appeared in the autumn of the same year; and, finally, in the spring of 1900 about ten more seeds germinated. No. 966 was sown on the 21st August, 1900; it commenced to germinate on the 17th September, 1900; and by the 11th October there were in the pot more than thirty plants of different sizes and germination was still proceeding, while by the 1st November the tallest plant was 3 cm. in height, and its 1st leaf was fully developed.
Description of Seedling.
Early development: By the time the cotyledons enclosed in the seed-coat, and usually also in the remains of the carpel, are just bursting through the ground the root and hypocotyl have developed considerably, and are almost indistinguishable except for the dense mass of very short hairs on the former.
[Footnote] * This form was first called attention to by Baron Von Mueller in his “Vegetation of the Chatham Islands,”, Melbourne, 1864, p. 11: “A carious variety of Sida lyallii, with small deeply incised leaves, collected by Mr. Travers and Dr. Haast in Middle Island, may be distinguished as var. ribifolia.”
At this stage the root and hypocotyl are together 11.5 mm. in length, and the root is 1.5 mm. in diameter. Next the hypocotyl grows upwards, and by the time it has risen arching out of the soil to a height of 5 mm. the green base of the cotyledons is appearing above the ground. The part of the hypocotyl which is arched downwards rapidly becomes straight, and the cotyledons enclosed entirely or partly by the seed-coat, and often by the remains of the carpel also, are raised with their laminæ closely pressed together and horizontal. The cotyledons grow rapidly in length and width, only the tip remaining enclosed in the seed-coat, which finally is cast off. Then the cotyledons open out, becoming horizontal or having their apices pointing downwards and their bases almost touching or sometimes even overlapping. As development proceeds the petioles lengthen considerably, until they finally become half the length of the laminæ, the bases of which are now 6 mm. or more apart. By this time the plants are twenty-four days old, and have roots 5.5 cm. in length, with cotyledons (lamina) 11 mm. × 10 mm., petioles 5.6 mm., and the 1st leaf is 8 mm. in length, with its lamina equalling the petiole and just unfolding.
Root of great length, deeply descending; lateral rootlets not numerous.
Hypocotyl at first tender, succulent, green and occasionally marked with pink, soon becoming stout and woody, terete, glabrous except for a few short hairs above, smooth, finally 16 mm. long and much thickened at the base.
Cotyledons (when fully grown) variable in size and shape, sometimes not of equal size on same plant; lamina 9 mm. × 9 mm. or thereabouts, rotund or obovate-rotund, often cuneate at the base; sometimes quite entire, but usually lobed or irregularly crenate on upper third of margin, pale-green, glabrous; nerves five; venation much reticulating; apex rounded; petioles spreading, 5 mm. in length, channelled on upper surface.
Before the cotyledons have emerged from the seed-coat they have their upper surfaces pressed closely together; the apical portions are folded together upon themselves, and bent so as to be closely enclosed by the conduplicately folded lower three-quarters of the lamina. This remains of the folding of the apical portion of the lamina may be seen in the fully expanded cotyledons, where towards the apex of the one is a slight depression, and towards the apex of the other a still more slight protuberance. Lord Avebury explains that this folding of the cotyledons in certain of the Malvaceæ causes the obscure lobes on the cotyledons.*
[Footnote] * “A Contribution to our Knowledge of Seedlings,” London, 1892, vol. i., pp. 40, 41, and 245, figs. 79, 80, 81, and 35.
1st leaf subcordate, irregularly and deeply crenate, almost lobed, ciliated with short hairs, also a few hairs on the petiole; remainder of leaf glabrous, pale apple-green on both surfaces, palmately 5-nerved, with the veins much reticulating; petiole three-quarters the length of lamina, channelled.
Later leaves up to 6th leaf broadly cordate, sometimes almost rotund, with cordate base; more or less lobed, sometimes almost trilobed; lobes irregularly crenate, ciliated; remainder of leaf as in description of 1st leaf.
Stipules inserted on stem on inner side of petiole, subulate, often stained pink; at first very soft and succulent, protecting young bud, afterwards smaller through drying, finally deciduous.
Stem of slow development, with early internodes very short (1st internode is 2 mm. long by time 1st leaf is 11 mm. long), terete, pale-green marked with purple, furnished with a few remote stellate hairs. In plant about eight months old the stem, exclusive of the now woody hypocotyl, is 14 mm. in length, still soft and succulent, green deeply stained with brownish-purple; later internodes considerably larger than the earlier ones; stellate hairs more numerous on upper portion than on lower portion of stem; from the lower internodes all the leaves have fallen, a few shrivelled stipules still persisting; the leaves above have all been developed since the winter.
Besides the above-described artificially raised seedlings, I have one which was collected at the base of Mount Torlesse in April, 1898, and which has been kept since that time in the shade-house. It is now 16 cm. tall, with three main stems, a few short side branches, and about fourteen leaves. The largest leaf is (lamina) 2.5 cm. × 2.6 cm., ovate, with cordate base; margin lobed and crenate; deepest lobes 5 mm. in depth; apex obtuse. The other leaves are smaller and more approaching reniform in outline, being considerably less drawn out at the apex. The stems of recent growth are twiggy and slender, with internodes ± 15 mm. in length. All last season's leaves fell off in the autumn or during the winter, notwithstanding the climate of the shade-house, a much milder one than that of the natural station of the plant.
There are two quite distinct forms of Gaya lyallii, one—Gr. lyallii proper—being confined, so far as I know, to regions in the South Island of New Zealand exposed to the great western rainfall; and the other form—i.e., the one now under consideration—being found without the limit of the above rainfall in the eastern lower mountain region, where it grows chiefly at the base or on the slopes of river-terraces or near the outskirts of the Fagus forest. The adult leaves of Gaya
ribifolia—I append only the varietal name, partly for sake of brevity and partly because it seems to me a perfectly distinct species, as Mr. D. Petrie suggested to me so long ago as January, 1893—vary considerably and are of two types: First, those which come close to the seedling leaves and are deeply lobed, sometimes of greater breadth than length and with the apex rounded and little drawn out; second, those of an ovate outline, with an apex much more acuminate, and with the lobes less deeply cut into the leaf than in the seedling forms, a leaf much resembling that of Gaya lyallii. In specimens from the Kaikoura Mountains the leaves are lobed much less than in my Canterbury specimens, and their apices are still more acuminate. All the adult leaves of Gaya ribifolia are covered on the under-surface with a mat of stellate hairs (Plate XII., fig. 46), which gives a whitish colour to that surface of the leaf, and almost hides the reticulating veins. The western plant, on the contrary, is bright apple-green on both surfaces, the stellate hairs being confined mainly to the principal veins. The individual hairs, moreover, are usually about half the length of those on the eastern plant. This difference in colour enables a thicket of either form of plant to be identified at a glance, even when the observer is quite a distance away. The western plant has its adult leaves not lobed, but only irregularly toothed, and the apex is always much drawn out.
I have not up to the present critically studied Gaya lyallii in the seedling form, but reversion leaves of that species are almost identical with some of the seedling leaves of G. ribifolia above described, and this shows that the two forms are very closely related; while possibly the more glabrous western form may be the ancestor of the tomentose eastern form, whose tomentum is clearly an adaptation to the drier character of its station. It is œcologically of extreme interest that a character seemingly so trivial as a slight variation in hairiness of leaf has led to these two species not having intermingled, although they approach in places to within only three or four miles from one another at most; and it shows, moreover, how an apparently unimportant character may govern the climatic distribution of a plant.* It may also be pointed out that both forms thrive equally well side by side in lowland gardens where the rainfall is slight, and that the characters of each, so far as I have been able to ascertain, remain unchanged.
[Footnote] * In a struggle for existence between these two plants it seems probable that each in its own domain would wipe out the other, unless the invader possessed a special power of rapid adaptation to the new conditions.
The seeds of Gaya ribifolia are ripe about the end of April, the plant having bloomed at the end of January and the beginning of February. They are almost invariably attacked by the larva of some insect, so that sometimes it is almost impossible to procure good seed. The carpels when ripe fall from the trees, under which quantities of seedling plants are often to be found. This leads to the occurrence of the plants usually in small clumps, with the trees close together, for, under ordinary circumstances, a seed will not get far from its parent tree, nor, if it did so, would it grow so easily and thrive as under the friendly shade. The western plant, on the other hand, forms much larger colonies, since those of its seeds which fall away from the protection of the parent have a much better chance to germinate in the moister western climate. The large cotyledons will be of great service in providing a food-supply for the quick growth of the root. One of the seedling plants had three cotyledons, and it is worthy of remark that this one developed more rapidly than did some others with normal cotyledons which germinated at the same time.
According to Sir Julius von Haast, Mr. T. Kirk,* and, others, Gaya lyallii is said to be deciduous at above 3,000 ft. and an evergreen at below that altitude. I have always much doubted that statement, but cannot as yet entirely disprove it. A tree of Gaya lyallii in my garden regularly loses its leaves, though some do not fall at times before the end of winter. Gaya ribifolia in the garden of Dr. A. Dendy, on the Port Hills, where it enjoys a much milder winter than in the lower mountain region, also loses its leaves. A plant in Mr. S. D. Barker's garden, originally from the Kaikoura Mountains, loses its leaves, and also seems to come into leaf later than the common type. Seedling plants in both greenhouse and shade-house are certainly deciduous. I fancy the idea of the plant remaining evergreen must have arisen from observers having seen trees late in autumn or early in winter still more or less leafy, but it may be possible that in the West Coast Sounds and similar regions the plant may be evergreen. However, this is for future observers to decide.
Plagianthus betulinus, A. Cunn. Plate X., figs. 11, 12, 13, 14, 15.
The young plants from which the description below was drawn up were growing under a parent tree, where the seed had fallen, in the Christchurch Botanic Garden, and were kindly given me for the purposes of this paper by Mr. A. L. Taylor. The leaves figured of the semi-shrubby form of this
[Footnote] * “Handbook,” pp. 30, 31; “Forest Flora,” p. 279.
plant are in part from the above-mentioned parent tree and in part from a young tree about eight years of age growing in my garden.
Description of Seedling.
Root appears to be of medium length and of rapid growth, but in all plants examined was broken.
Hypocotyl 30 mm. long—probably owing to being “drawn up,” for the seedlings were crowded amongst grass, &c.—terete, white, hairy above.
Cotyledons more or less rotund; upper part of margin deeply crenate or lobed, ciliated; lamina 8 mm. × 7 mm.; petiole semierect, hairy, 3 mm. long.
Early leaves (figs. 12, 14) somewhat variable in size, but all of one type; ovate, often more or less truncate at base, or sometimes subcordate; lamina ± 19 mm. × ± 16 mm., lobed or bicrenate, bright yellowish-green on upper paler on under surface, palmately 5-nerved, with ultimate veins much reticulating, ciliated on margin, and with a few stellate hairs on veins, especially on those of under-surface; margin of crenations often stained with purple; petiole almost half as long again as lamina, slender, channelled above, but not deeply.
Stipules at first quite enclosing young bud, finally deciduous; linear, 3 mm. × 1 mm., inserted on stem at upper side of base of petiole.
Stem erect, with erect branches, and exhibiting no sign of a second shrubby stage, even in seedlings 12 cm. tall; terete, brown, hoary in places, with numerous stellate hairs; internodes ± 10 mm. long.
Further development: After remaining in the erect form for a certain time, and reaching a certain height (but of this I can as yet give no definite information), the plant assumes a semi-shrubby habit. The branches which are now developed are long, twiggy, and flexuous, hanging downwards and interlacing one with the other, their apices at the same time often bending upwards. The leaves produced on these branches are very much reduced in size, and in many cases occur in fascicles on very short reduced branches. In shape they present all kinds of gradations, from very small rounded often cuneate leaves, toothed or lobed (figs. 13, 15), to forms approaching the ovate or ovate-lanceolate acuminate adult type of leaf.* Finally, after several years usually, the plant undergoes a third change, when it assumes a true arboreal habit, its branches no longer interlacing and weeping, but growing upright, at first in a rather fastigiate manner, and in this final stage resembling, so far as erect habit is concerned and type of leaf, the first stage of development.
[Footnote] * See also Kirk, l.c., p. 207, and plate 103.
This passing of a plant through three stages, of which the first and the final are not very different, is a phenomenon of extreme interest, to which I have briefly called attention before.* In dealing with the Chatham Island form of P. betulinus—which I may here point out does not go through the semi-shrubby form at all—this matter is gone into at some length, and I propound a theory to account for this wonderful difference between two plants so closely related that botanists up to the present time have not accorded the Chatham Island plant even varietal rank.† I will here only point out that the semi-shrubby form much resembles in habit and general appearance the adult form of many New Zealand xerophilous shrubs of dry stations, and of some of which I have already treated.‡ In my garden a tree which I grew from seed, now about eight years of age, is shrubby below, with weeping interlacing twigs up to a height of 1.25 m.; above this for a height of 0.30 m. the plant is still shrubby, but the twigs are erect and not drooping, while the remaining 0.45 m. has assumed the final arboreal habit, with thicker hardly flexuous branches passing upwards from the stem at an angle of 45° or less, and with the leaves of the final shape, but not yet of so great size as in an older plant. This appearance of the semi-shrubby form below and of the tree form above persists for a long time, and may be seen in trees long after they have attained to their full development. I do not think that the semi-shrubby portion ever produces flowers, but this is a matter which deserves inquiry.§
No. 1072. Plagianthus betulinus, A. Cunn. (Chatham Islands var.). Plate XI., figs. 16–20.
The plants were grown from seed which ripened on a specimen with seemingly immature fruit kindly given to me by Mr. S. D. Barker, and collected by Mrs. Chudleigh in the Chatham Islands. The greater part of the description is drawn up from a number of living seedling and young plants sent to me from the Chatham Islands by Mr. F. A. D. Cox.
[Footnote] * l.c., p. 358.
[Footnote] † Kirk, “Student's Flora,” 1899, p. 71. Mueller, l.c., p. 10: “Leaves and calyces larger than the specimens in our museum.” Buchanan, “On the Botany of the Chatham Islands” (Trans. N.Z. Inst., vol. viii., 1875, p. 334).
[Footnote] ‡ l.c., pp. 362, 385, 388, 390. It would perhaps be more correct to describe this semi-shrubby form as a transition between these extreme xerophilous forms and a low-growing tree of an ordinary erect habit.
[Footnote] § Goebel states, “Organography of Plants,” English edition, Oxford, 1900, p. 154, that the fixed juvenile forms of certain Gymnospermæ “are usually unable to produce sexual organs, although external conditions are quite favourable for this when they have attained an age and a size at which the normal plants are and have been for long sexually mature.”
The seed was sown on the 20th August, 1900; it germinated on the 27th September, and by the 1st November the tallest plant was 2.25 cm. in height, with the lamina of its 1st leaf just opened out.
Description of Seedling.
Root slender, pale, very easily broken, about 25 mm. long in plant 16 mm., tall.
Hypocotyl 18mm. long, glabrous and pale for lower quarter, green and hairy on upper three-quarters, with hairs projecting horizontally; terete, erect.
Cotyledons rotund, entire for lower half of margin, with remainder of margin lobed, in one instance merely crenate; ciliated with hairs similar to those on hypocotyl, palmately 5-nerved, with nerves near base rather obscure; green on upper and paler on under surface, horizontal or with apicesbent slightly downwards; lamina 9mm. × 9 mm., or not quite so broad; petiole channelled, but not deeply, on upper surface, rounded on under-surface, 3 mm. long, hairy.
Plants collected in Chatham Islands by Mr. Cox. The tallest examined was 15.5 cm. tall and the smallest 6.5 cm., with four persistent leaves and four leaf-scars, the lowest leaf therefore being the 5th seedling leaf.
Stem (in smallest plant) rather thicker at base than above, brown, slightly pubescent with stellate hairs, especially in youngest portion.
5th leaf shallowly 3-lobed, with the lobes deeply and coarsely crenate, petiolate; lamina 15 mm. × 15 mm. in broadest part, broadly ovate, truncate at base (fig. 17), bright pale-green, ciliated with short pale-coloured hairs, palmately 5-nerved, with ultimate veins much reticulating; petiole 12 mm. long, forming angle of 45° with stem, terete, pale, pubescent with stellate hairs.
Other leaves (figs. 18, 19, 20) very similar to above, but cordate at base, and often with hairs on upper surface.
Upper portion of stem green, stipules well developed, especially those at the growing-point, which are of full size much before the leaf is developed fully.
Stipules 3 mm. × 1.5 mm., linear, brown, acute, hairy, soon wither.
Leaves on older plants very similar to those already described, of average size of 16 mm. × 17 mm. in broadest part, truncate or cordate at base, often obscurely 3-lobed.
Later leaves on plant 15.5 cm. tall 30mm. × 30mm. in broadest part, cordate, tapering towards apex; petiole 30mm. Other features as before (fig. 18).
The similarity of appearance in form between the seedling and adult leaves of Plagianthus betulinus of the Chatham
Islands was pointed out to me about a year ago by Mr. S. D. Barker, in whose garden I had the pleasure of seeing some seedling plants sent to him by Mrs. Chudleigh. Shortly afterwards I received from Mr. F. A. D. Cox the fine collection of young plants from which the above description was drawn up. Thinking that possibly, in common with Pseudopanax chathamica,* the Chatham Island form of Plagianthus betulinus, and perhaps other plants which pass through three stages in New Zealand proper, did not go through the three stages described above in this paper through which P. betulinus of New Zealand passes, I wrote to Mr. Cox for information on this point, so important in the life-history of the plant. The following is a copy of Mr. Cox's reply, under date of the 6th October, 1900: “Plagianthus betulinus.—This certainly does not pass through the stages you have mentioned; as far as I have observed branches and twigs are always upright, as in the mature form, and leaves always the same shape; the appearance you mention of apparently two distinct plants in regard to foliage, &c., is absent. Sophora tetraptera never alters its form; tiny seedlings have the leaves (of course, in a smaller form) identically the same as in the mature tree; the only Chatham Island plant that has two distinct forms of leaves—broad and narrow—on the same plant is Dracophyllum scoparium.”†
If what Mr. Cox states is correct—and it is most unlikely that so accurate and keen an observer can be mistaken—then the question opened up as to the reason of this great difference in the life-history of a certain species according as it is indigenous to New Zealand or to the Chatham Islands is one of the greatest interest, but at the same time of the most extreme difficulty. The theory which I am about briefly to outline as an explanation of this phenomenon is the merest hypothesis, and put forward chiefly as a basis on which inquiries can be made, not in botany alone, but also in geology and zoology, so that, whether the theory be eventually sustained or shown to be false, its examination may lead to the publication of facts of considerable scientific importance.
[Footnote] * Cockayne, Trans. N.Z. Inst., vol. xxxii., 1899, p. 89; and Kirk, “Student's Flora,” p. 223.
[Footnote] † In what follows the heterophyllism of D. scoparium need not be taken into account, for I think it can be explained on quite local grounds, which it would be out of place to enter into here.
[Footnote] ‡ l.c., p. 356.
[Footnote] § Strasburger, “A Text-book of Botany,” London and New York, 1898, p. 46.
development of an individual a certain phase occurs, the more recently must the condition that the phase in question represents have been the fixed form of the species. Professor W. F. Ganong goes into this matter at some length and with great clearness.* “Of course, in any given generation the embryo,† apart from slight irritable responses to light, &c. is determined by heredity. But heredity is but the sum and resultant of past experiences, and hence in the present case is largely a study of past environments. This suggests an explanation which I believe to be the true one—i.e., that the form of the adults, like that of any other character once acquired—it matters not for our present purpose how—as it becomes more and more fixed and intensified tends to work back into earlier and earlier stages in the ontogeny of the successive individuals, until finally a character adaptively acquired by the adults works back into the epicotyl and finally into the embryo itself.” Further on he writes “of characters acquired by adaptation in the adults sweeping back into the later seedlings and wiping out earlier characters.” According to the above that semi-shrubby form of Plagianthus betulinus of New Zealand, which remains for a long time in the ontogeny of that plant as a seemingly adult form, and, moreover, persists for a long time even after the real adult form has appeared, must have been the final form of the plant at no very distant date, geologically speaking. But it cannot have remained a fixed form for any great length of time, for it did not work back into the epicotyl, and so wipe out the earlier stage which so much resembles the final one. In the Chatham Island plant, on the other hand, the first seedling form being so little different from the final shows that the latter has endured for a very long time, nor, so far as the first form tells us, has ever undergone much change since it first became fixed. But the first seedling form of the Chatham Island and of the New Zealand plant are very similar, and so we can well conceive that a plant almost identical with the Chatham Island form was the ancestor of the New Zealand form. The same reasoning would apply to Sophora tetraptera (using the specific name in its widest sense), which is even a more instructive species. For one variety of that species not only goes through three forms in the course of its ontogeny, each much resembling in habit
[Footnote] * “Annals of Botany,” 1898, vol. xii., “Contributions to a Knowledge of the Morphology and œcology of the Cactaceæ: II. The Comparative Morphology of the Embryos and Seedlings,” pp. 467, 468.
[Footnote] † “We may best speak of the stage where the embryo is lying in the seed as that of the ungerminated embryo, and that in which it has come out, turned green, spread its cotyledons, but before it shows the epicotyl, as that of the germinated embryo” (Ganong, l.c., p. 431).
those of P. betulinus, but in certain dry regions of the South Island the intermediate shrubby, or I may call it the xerophilous form, undergoes no further change, and is considered by some botanists a distinct species.* On the contrary, the Chatham Island plant, and perhaps also one of the North Island varieties, passes through no xerophilous form. Here again, then, the Chatham Island plant resembles the ancestral form. There are few plants in New Zealand more xerophytic in structure than the various species of Aciphylla. The seedling forms of A. squarrosa and A. colensoi have, however, quite flaccid and grass-like leaves. In the Chatham Islands, Mr. Cox tells me, Aciphylla traversii has leaves sufficiently soft and flaccid for sheep to eat them greedily. Such an Aciphylla would probably much resemble the ancestor of the New Zealand forms. On the dry table-lands of the South Island of New Zealand, and in various parts of the North Island where the soil is poor and where the rainfall is low, the character of the vegetation is xerophytic, many of the shrubs showing, for instance, a common adaptation to the environment in their much divaricating interlaced wiry branches; in fact, they resemble very much indeed the semi-shrubby stage of Hoheria, Plagianthus betulinus, Pennantia corymbosa, and Sophora tetraptera. Xerophilous as these former shrubs are, a very slight change of environment, such as the shelter of a forest, will alter them in the most marked manner (see above regarding Pittosporum rigidum, and what follows re Rubus pauperatus). An extract from my note-book, taken in the “bush” at the lower gorge of the Waimakariri, is of interest in this connection: “Very worthy of note is a young plant of Corokia cotoneaster“—a most densely growing shrub under normal conditions—“assuming a semi-tree-like habit. At this stage the stem is erect, the branches pointing upwards and outwards, twisted and drooping at their extremities. It much more resembles the transitional form between the semi-shrubby stage of P. betulinus and the mature form of that plant than it does its own normal form as growing in the open.”
If the early seedling form of a number of these xerophilous shrubs be examined it will be seen, as I have shown in some instances,† that they are at first erect, with a much more considerable leaf development than the adult, and altogether better adapted for more hygrophytic conditions. That is to say, the majority of the scrubby plants of river-terraces, stony flats, and the like, might well be descended from ancestors which lived in a moister climate. Dr. L. Diels‡ was the first
[Footnote] * Sophora prostrata, Buchanan.
[Footnote] † See, for instance, l.c., pp. 91, 92, 93.
[Footnote] ‡ “Vegetations—Biologie von Neu-Seeland,” Leipzig, 1896, pp. 246, 247, and 296.
to offer a suggestion as to the causes which had led to the evolution of this xerophilous vegetation. In the first place, he considered its extreme xerophytic character to be not at all in accordance with its present environment, especially as far as climate was concerned. He therefore turned to the geological history of New Zealand, and based his conclusions on the theory of Captain F. W. Hutton*—viz., that a great elevation of the land took place during the Pliocene period, by which the Southern Alps would be raised to a height much greater than the present; and, to quote from Captain F. W. Hutton's latest utterance,† “All the islands were joined together, and the land stretched away to the east and south so as to include the Chatham and Auckland Islands, as well, perhaps, as Campbell and Macquarie Islands, whilst to the north it certainly extended to the Kermadecs, and perhaps much further. On the mountains of the South Island large glaciers were formed, and the torrential rivers running from them tore into disconnected fragments the Miocene marine rocks which obstructed their valleys.” According to Diels this elevation of the mountains would lead to a much smaller rainfall on the then high table-lands and plains stretching to the mountains of the Chatham Islands in the east, and the consequence would be a steppe climate.‡
As a consequence of the extreme dryness of this region many of its plant inhabitants would migrate to wetter localities, while those that remained would become either modified so as to resist the gradually increasing drought or would perish. Those plants which became so adapted Diels calls “the descendants of the forest flora,”§ and he points out in support of his argument how Schenk and Warming have shown that lianes of the forest can become shrubs of the plain∥ Captain F. W. Hutton also considers the above suggestion worthy of examination, for he writes (l.c., p. 182): “It is possible that this large extension of land to the eastward may have produced desert-or steppe-like conditions in a portion of New Zealand, evidence of which some botanists think they find in our flora.”
If we accept these views of Diels and Hutton, then three
[Footnote] * First propounded in Trans. N.Z. Inst., vol. v., p. 385; further elaborated Trans. N.Z. Inst., vol. viii., 1876, p. 383, et seq., and in Annals and Mag. of Nat. Hist., ser. v., vol. xv., p. 77, et seq.
[Footnote] † “The Geological History of New Zealand” (Trans. N.Z. Inst., vol. xxxii., 1899, p. 182).
[Footnote] ‡ l.c., p. 296.
[Footnote] § l.c., p. 246, “Abkömmlinge der Waldflora.” These include certain species of Clematis, Pittosporum, Rubus, Carmichaelia, Notospartium, Aristotelia, Hymenanthera, and Corokia.
[Footnote] ∥ See also remarks in this paper re Rubus pauperatus and Pittosporum rigidum.
havens of refuge would be open to those forest-trees and other plants which could not tolerate the increasing dryness of climate, viz.; The region west of the Southern Alps and of the central ranges of the North Island, and which would then, as now, support a dense forest population; the warmer and moister regions of the North; and the eastern coast, part of which would include the then high lands of the Chatham Islands. These islands, having been in the Miocene period below the level of the sea, would possess no inhabitants to resist the invaders, consequently a purely Pliocene vegetation would there settle down and possibly undergo little change in the equable climate, as evidenced by early seedling forms of the present plants showing so great a resemblance to the present adult form. How long the connection between the Chathams and New Zealand existed, or whether the two lands were ever actually united or separated merely by a very narrow strait, geologists have not been able yet to determine. It seems clear, however, that when a subsidence of the land took place, then very soon the Chathams would be isolated sufficiently to receive very few plant immigrants, while yet steppe conditions would reign over much of eastern New Zealand. Finally, the subsidence continuing, New Zealand would sink, either in part or as a whole, to nearly 300 m. below its present level,* which would reduce the area very considerably, rendering many of the mountain passes of the South Island no barrier† to the intermixing of eastern and western plants, while in the North Island there would be less obstruction still. Between the plants of the forest and those of the desert the struggle must have been fierce, and the most extreme xerophytes must have perished or taken refuge in the most barren place, where, indeed, we find them at the present day, on shingle-slips, dry rocks, stony plains, river-beds, &c.‡ In this struggle those plants which had never become fully adapted to extreme xerophilytic conditions, such as Plagianthus betulinus, Sophora tetraptera, &c., and which possess great powers of adaptability by assuming quickly either a hygrophilous or a xerophilous form according to circumstances,§ would, I take it, be able in the struggle for existence finally to vanquish their Pliocene ancestors which would oppose them in the west or advance
[Footnote] * Hutton, “On the Lower Gorge of the Waimakariri” (Trans. N.Z. Inst., vol. xvi., 1883, pp. 453, 454).
[Footnote] † Haast Pass, Arthur's Pass, Walker's Pass, Worseley Pass, Hurunui Pass, Amuri Pass, Cannibal Gorge, &c.
[Footnote] ‡ Such plants are Carmichaelia crassicaule, Raoulia eximia and its allies, the plants of shingle-slips, Ozothamnus coralloides, O. selago, O. microphyllus, O. depressus, Epilobium crassum, Hectorella cæspitosa, &c.
[Footnote] § Several examples are to be found in this and in my previous papers on New Zealand seedlings.
against them in the east. The very limited area in which the final struggle would take place would also much favour those better equipped for the fight. Also, the plants in question are not usually plants of the dense forest, but rather of its out-skirts, where even at the present day in a region so wet as Westland the conditions are essentially favourable to semi-xerophilous vegetation.* Hybridization might also play a part, for in the third stage of these plants we have almost the ancestral stage reproduced, or, as I put it in a former paper, “reinstatement of a species.”† On the Chatham Islands this struggle between eastern and western plants, between xerophytes and hygrophytes, can never have taken place, and the only struggle must have been between the Pliocene plants themselves, and any evolutionary changes would be owing to local conditions. That these conditions have had little effect seems proved by the fact that the seedlings of Chatham Island plants show so few changes during their development. Thus the present vegetation of the Chatham Islands may in large measure be almost the same as that which occupied New Zealand in the older Pliocene period.
Other facts seem to support the above view, such as the distribution of Myosotidium nobile and of the macrocephalous Olearias, &c., but I reserve the whole matter for fuller treatment.
I must not close this particular portion of my subject without expressing my very great obligation to Captain F. W. Hutton for much valuable advice and assistance in this matter.‡
No. 779. Veronica odora, Hook. f. Plate XI., figs. 21–26. (Syn. V. buxifolia, Benth., var. odora, T. Kirk, in Trans. N.Z. Inst., vol. xxviii., p. 524.)
The seed was collected on the 26th February, 1899, from plants growing on Mount Isabel, Hanmer Plains district, at an altitude of 970m. It was sown on the 4th September, 1899, and commenced to germinate on the 1st November, 1899, but, although a large proportion of the seeds had germinated within four weeks or so from that date, some did not do so until the spring of 1900. The seeds were in part sown while still enclosed in their capsules. This is a very useful method to employ when the capsules are removed from the plant before the seeds are fully developed, since seeds capable of germination may be thus often procured from plants grow-
[Footnote] * Cockayne, l.c., p. 133.
[Footnote] † l.c., p. 359.
[Footnote] ‡ The author writes from the Chatham Islands, under date 9th January, 1901, as follows: “Since examining the vegetation here my views have become somewhat modified.”—Ed.
ing in regions difficult of access, and which it might not be practicable to again visit when the seed was fully matured.* It is advisable, therefore, in many instances to collect immature fruits of Veronica, not removing the capsules from the inflorescence, even when so little developed that it might seem quite hopeless† for the seed to reach maturity. From seed germinating inside the capsule young plants will be developed in all respects similar to those from seed sown in the usual manner, except that the root will be coiled round and round within the capsule. In the case of the seedlings under consideration, one of the plants examined had its roots coiled up like a watch-spring, which, when unrolled, gave a measurement of 21 mm. The hypocotyl of this plant measured 3.5 mm. in length, and the cotyledons were 3 mm. × 2mm. The root was of a brownish colour, and provided with numerous root-hairs.
Description of Seedling.
Hypocotyl very soft and juicy at first, pale-green, semi-translucent, glabrous, varying in length according to position with regard to light, those seedlings in shade of other plants, &c., having much longer hypocotyls than those more exposed to the light. The longest hypocotyl observed was 11 mm. long.
Plant described below 9 mm. tall, and having cotyledons and four pairs of leaves. A fairly typical seedling.
Cotyledons furnished with petioles connate at the base; laminæ 3 mm. × 2 mm., ovate-oblong, entire, obtuse; upper surface green; under-surface purple except at margin, round which is a narrow band of green; petioles 0.75mm. long. channelled above, rounded on under-surface.
1st pair of leaves (fig. 21) soft, juicy, and rather thick, with petioles connate at base, very broadly ovate-rotund; laminæ 3 mm. × 2.5 mm., entire, acute or subacute; upper surface dull-green, furnished with numerous short white hairs; under-surface purple except towards margin, round which is a green belt; margin entire, ciliated with hairs similar to those on the upper surface.
2nd pair of leaves very similar in most respects to the 1st pair, but margin is not entire, having one tooth on each side. The leaf figured (fig. 22) is narrower than is usually the case.
3rd pair of leaves have petioles more erect—i.e., given off-from the stem at a more acute angle—than in 2nd pair of
[Footnote] * This plan of sowing is briefly referred to in a former paper, l.c., p. 83.
[Footnote] † Mr. S. D. Barker tells me that he has also had good results from sowing seemingly unripe seed.
leaves, thus raising the horizontal laminæ so that they do not shade the leaves below, whose petioles, being given off at a wider angle, also help to throw the lower leaves out of the shade of the upper ones. (In older seedling plants the lower-most leaves have in addition their laminæ bent downwards towards the ground for the same purpose, while the very uppermost are on a level and almost horizontal. In the youngest plants the length of the lower internodes as compared with the very short apical ones serves the same purpose.)
Laminæ of 3rd pair of leaves (fig. 23) 3.15mm. × 3 mm., broadly ovate; on each margin is one large tooth with a blunt swollen apex; petioles two-thirds the length of laminæ; other features of leaves as before.
4th pair of leaves similar in most respects to those previously described, but with the toothing still more strongly marked.
Stem terete, with two opposite rows of hairs on each internode similar to the leaf-hairs, those on the one internode alternating with those on the next above; 1st internode 2mm. long, 2nd internode 1.9 mm. long, and so on, the internodes becoming much shorter towards the growing-point of the shoot.
Further development (as observed from older seedlings): The leaves continue for some time of the same type.
Anomalous seedling: One of the seedlings having cotyledons and three pairs of leaves; these latter are quite entire, and of same type as the 1st pair of leaves.
Plant with 18 pairs of leaves: In this plant, which may be taken as a typical seedling, the leaves from the 5th pair to the 9th pair (fig. 25) gradually increase in size, reaching a maximum of (lamina) 5.5 mm. by 3.75 mm., with petiole 1.75 mm., and having one or two teeth on each margin. The midrib is now quite prominent on the under-surface of the leaf, which in nearly every seedling (with hardly an exception) is dark-purple. The petioles are rather broad, channelled on upper surface, swollen and connate at base, where it is stained reddish-purple in a ring round the leaf-base. Commencing at about the 10th leaf and proceeding upwards, the leaves gradually decrease in size, and are much narrower than those below, otherwise they are as in the previously described leaves. The particular plant described above has developed a lateral shoot from the axil of the now withered cotyledon; all the leaves of this shoot are of the same type as the 1st pair of leaves. The internodes are short, ± 1 mm., and partly sheathed by the leaf-base.
Besides the Mount Isabel seedlings, I have also some older ones grown from seed collected from a plant in my garden, originally from Mount. Maungatua, Taieri, Otago, which was
kindly given to me some years ago by Mr. Henry J. Matthews, Chief Government Forester. The early seedling leaves are of the usual type, with entire margins. The later leaves are also of the same type as those described above, but usually wider (fig. 24). Plants 4 cm. tall have the leaves of the adult type oblong, sometimes oval, quite entire, coriaceous, almost glabrous, any hairs on upper third of margin most minute; lamina 5.5 mm. × 3.80 mm., obscurely keeled, tapering into petiole, not truncate; petiole 1 mm. long. The adult leaf of the parent is very similar but larger, with lamina 8 mm. × 5 mm., and with base truncate. Very probably had these young plants been growing in the open, and not in the greenhouse, the final leaves would have appeared at an earlier stage.
Mr. T. Kirk (l.c., p. 524) included V. odora, Hook, f., as a variety of V. buxifolia Benth., thus differing from Sir Joseph Hooker, who had previously, in the “Handbook of the New Zealand Flora,” p. 210, given V. odora as a synonym of V. buxifolia. Whether the plant under discussion is identical with the Auckland and Campbell Island plant originally described and figured in the “Flora Antarctica,” p. 62, tab. 41, under the name of V. odora I am not in a position to say; but I am certainly well acquainted with two quite distinct plants—viz., the one under consideration, which forms thickets at times in moist shady places in the lower subalpine region of the South Island, often in wet places taking the place of the ordinary mixed subalpine scrub, or when isolated is a bush 1 m. or less in height, of a ball-like aspect;* and the other a plant hardly branching, and certainly never forming a round bushy its main stem partly prostrate beneath the soil, and the ascending portion bearing a few short erect branches, and reaching at most a height of 0.5m., or in many cases much less. Its leaves, too, are much thicker and more coriaceous than those of V. odora, and its spike very few-flowered. Also, it does not occur in the lower but only in the upper subalpine region, on wet grassy slopes. Of course, it is all a matter of opinion whether a systematic botanist would consider-these two plants distinct species, but œcologically they are very distinct indeed, and from that point of view must be treated of separately. The two forms, so far as I know, are never found mixed together; so here we have another example of a slightly more xerophytic structure keeping two very closely allied forms distinct from one another as to their habitats.
I have pointed out elsewhere how greatly V. odora varies.†
[Footnote] * Cockayne, l.c., p. 121.
[Footnote] † “On the Burning and Reproduction of Subalpine Scrub” (Trans N.Z. Inst., vol. xxxi., p. 417).
This variation chiefly concerns form of leaf, imbricating of leaves or the contrary, and length of internodes. Amongst a number of plants of which an exact measurement of leaf, &c., was taken by me the largest leaf measured 14.5 mm. × 5 mm, and the smallest 6 mm. × 4 mm., a difference of 8.5mm. in length and of only 1 mm. in breadth. The proportion of length to width varied considerably in other cases; for instance, 2: 1, 3: 2, 3: 1, and 5: 3, &c. The longest internode was 4.75 mm. and the shortest 1.5 mm. Of sixteen plants examined, five had imbricating leaves and eleven had patent leaves, while only two had leaves of the same size and none had internodes of the same length. The leaves also varied very much in the degree of concavity of the upper surface or the degree of rounding or drawing out of the apical end. From the above it can be seen how great the variation is amongst individuals of V. odora. How far these individuals reproduce themselves “true” from seed, or, if they vary, how great is the proportion of variation in a certain direction, such as in the important œcological difference of patent or imbricating leaves, is a matter of considerable interest, and requires much careful and patient work. V. traversii, as I pointed out before,* does not individually produce itself “true” from seed, and the like is to be expected in all these variable Veronicas.
The seedling leaf-form of V. odora consists of, first, a very early appearing entire ciliated leaf, and, second, of a leaf more or less deeply toothed and ciliated. The first form much resembles that of V. traversii and some other Veronicas, but whether it be an approximation to the ancestral leaf-form of a certain section of Veronica cannot, with our present knowledge of seedling forms of this genus in New Zealand, be determined. The adult form of leaf is evidently an adaptation to its environment, the cold wet station of the plant being most likely physiologically dry. Cultivated plants grow in my garden in stations so dry as a sand-dune; one particular plant has occupied such a position now for eight years, and has received no artificial water-supply. The seedling leaves, on the other hand, are adapted for moister conditions. In the shade-house a plant from Mount Torlesse has produced for the past two years toothed ciliated leaves resembling a 2nd seedling leaf, while a few of the youngest leaves have at present entire ciliated leaves similar to the 1st seedling. A species with such capabilities for adaptation to a wet or a dry climate should easily conquer in the struggle for existence a closely allied species without such adaptive capabilities.
[Footnote] * l.c., p. 377.
Veronica squalida, T. Kirk. Plate XI., figs. 36, 37.
The seed was given to me by Mr. A. L. Taylor, who gathered it from one plant in the Botanic Garden, Christchurch. This plant was originally sent to the above garden by Mr. T. Kirk at about the time when he first published the species. The seed was sown on the 6th June, 1899, and germinated on the 14th June, 1899.
Description of Seedling.
Early development: The hypocotyl emerges from the seed-coat and becomes developed considerably before the cotyledons appear. The cotyledons at this stage are arched downwards, enclosed in the seed-coat. The hypocotyl becomes slightly thickened at the base, and puts forth a great number of long minute hairs, which, together with the now descending root, fix the plant in position. Next the cotyledons open out horizontally. At this stage the cotyledons are sessile, oblong, 2.75 mm. × 1.75 mm., and the root is furnished with numbers of root-hairs, to which the particles of earth adhere in masses. The hypocotyl, at first white, is now green, and 2mm. in length. By the 30th November, 1899—i.e., in about five months and a half—the largest plants had attained to a height of 18 mm., and were furnished with three pairs of leaves; the cotyledons also were still present.
Plant described 18 mm. tall.
Boot fibrous, with numerous lateral rootlets.
Hypocotyl stout, terete, almost glabrous.
Cotyledons ovate or ovate-oblong, entire, green, often much stained with purple (this purple staining is very common in Veronica), glabrous, with petioles connate and channelled above.
Leaves opposite, decussate, entire or with one or two teeth on each margin, ciliated with short hairs curved at the apex; lamina green on upper purple on under surface, and with purple margin, tapering into the petiole; midrib prominent on under surface; petioles half the length of lamina, channelled on upper surface, connate at base.
1st pair of leaves ovate, usually quite entire.
2nd pair of leaves (lamina) 9 mm. × 5 mm.; petiole 2 mm. long.
Succeeding leaves become more narrow, still usually with one or two teeth.
At a further stage of development the leaves become linear-obovate or linear-lanceolate, usually with one or two teeth towards apical end of leaf, dull-green above, often purple beneath, ciliated with very short hairs; lamina tapering into petiole, 2.2 cm. × 7 mm.; petiole 5 mm., rather broad and channelled above.
By the time a plant is 18 cm. tall and furnished with several branches most of the early leaves have fallen off, and those now being produced are of the adult linear type and almost sessile, with scabrid margin, and measuring 4.4cm.X 5.5 mm.
The stem in these older seedlings is minutely pubescent, often much stained with purple; internodes ± 12 mm.
I have never seen the plant in its natural station. Mr. T. Kirk merely gives “Nelson—Matori and Wairoa. Valley”* as the habitat, so I can say nothing as to the conditions under which it grows, † The leaf changes are of interest from the petiolate, ovate, toothed leaf, 9 mm. × 5 mm., to the narrow obovate leaf, and finally to the very distinct almost sessile linear, or, according to Kirk's description, “narrow linear-lanceolate,” leaf, which is quite glabrous and entire, and 5.7 cm. × 6mm. The early type of leaf (fig. 37) much resembles that of the same stage of V. traversii.
No. 692 bis. Veronica armstrongii, T. Kirk. Plate XI., figs. 27–35.
The seed was collected from a cultivated plant in my garden, and sown on the 1st September, 1899. Germination took place from the 12th September, 1899, until the 30th October of the same year, and even then seeds were still germinating.
Description of Seedling.
Early development: The primary root and hypocotyl emerge from the seed-coat, and when they together about equal the latter in length the root bends downwards with its extremity to the ground. The hypocotyl then lengthens considerably, and from its base a ring of short fixing-hairs are developed; then the root pushes into the ground and grows downwards rapidly, while at the same time the cotyledons escape from the half-decayed seed-coat and open out horizontally to the light. The cotyledons rapidly increase in size, and the 1st two leaves make their appearance. Both cotyledons and leaves increase in size, the latter becoming much more toothed, and their petioles increasing in length and protecting the 2nd pair of leaves, which are now making their appearance, but still quite hidden between the two erect petioles. These petioles lengthen and open out, becoming further apart as the 2nd pair of leaves develope, while at the same time the 1st internode slightly increases in length. As the blades of the 1st pair of leaves grow the teeth also
[Footnote] * l.c., p. 528.
[Footnote] † I have also in my herbarium a plant which Mr. D. Petrie sent to me, collected at Whakatane, Auckland, which seems to be this species.
increase in size, until the leaf finally attains to the form shown in fig. 27. The 2nd pair of leaves are at first quite sessile and linear; as they become broader they are raised from between the protecting petioles of the 1st pair of leaves by their own petioles lengthening, which now, in like manner, protect the developing 3rd pair of leaves. At this stage the 2nd and 3rd internodes are hardly visible. After three months' growth the tallest seedling was 6 mm. above the ground, with two pairs of fully developed leaves, and the 3rd pair in process of development. After twelve months' growth a young plant is 2.8 cm. tall, with a root 6.8 cm. in length. This latter would probably have been longer had the pot been deeper. It has seventeen pairs of leaves, all of which are petiolate, very deeply toothed or pinnatifid, one lateral shoot from the axil of one of the 2nd pair of leaves, and three lateral shoots, with each one pair of leaves, from the axil of leaves near the apex of the main shoot. The leaf-blades are nearly all horizontal, but the upper ones point slightly upwards, and the lower ones are bent slightly downwards, in order to accommodate themselves to the light-supply.
Plant 6 mm. tall with two pairs of fully developed leaves.
Primary root 3 cm. long at least, pale-coloured, slender, with many lateral rootlets. It is very difficult to dig up a seedling without breaking the root.
Hypocotyl 4 mm. or 5 mm. in length, erect, stout, terete, glabrous, green or slightly tinged with red.
Cotyledons 4mm. × 2 mm., ovate, entire, obtuse, glabrous, soft and rather succulent; petioles flattened above, half the length of lamina, inserted at about angle of 45°, connate at base.
1st pair of leaves variable in shape and size, 4 mm. or 5 mm. long × 2 mm. to 2.75 mm. broad, ovate or oblong-ovate, rounded or cuneate at base, fleshy, green, toothed rather deeply with one or two teeth on each side; petioles two-thirds the length of lamina, flattened and slightly channelled above, connate at base; midrib more or less raised on under-surface of leaf.
2nd pair of leaves very similar to 1st pair, but very deeply toothed with two or three teeth on each side, or almost pinnatifid.
Stem green, very soft and juicy, hardly developed except for 1st internode, bifariously pubescent; 1st internode 1mm. in length or a little longer.
General description of a seedling leaf (figs. 28, 29, 35): From lanceolate to ovate or ovate-oblong in outline, often cuneate at base, usually very deeply toothed with one, two, or three teeth on each side, at times almost pinnatifid (fig. 35); acute, glabrous, usually bright-green on both surfaces of
lamina, though often stained with purple, especially on teeth; petiole from half to three-quarters the length of lamina, flat on upper surface, connate and sheathing just at base, which is slightly swollen and often purple-stained.
Stem in plant one year old green, often stained with purple near nodes, terete, slightly hairy below with whitish hairs pressed upwards against the stem; hairs above in two opposite rows, those on one internode alternating with those on the next above; internodes often 1.5 mm. long, but variable in length.
Veronica armstrongii is a shrub reaching barely 1 m. in height. Its very much reduced leaves are so closely compressed to the stem above and so intimately united with the bark below that the plant appears at a cursory glance as if leafless. Diels* has called attention to our want of knowledge as to the morphological significance of these reduced leaves, and that it is important to determine whether they are leaf-blades or phyllodes. Certainly, so far as their appearance goes they might very well be the latter. But a study of the seedling form shows a great many transitional changes between petiolate deeply toothed leaves and such as are sessile and entire (see figs. 27–34). The toothing gradually becomes more and more shallow and the teeth fewer in number, until finally they are altogether wanting, and we have only an entire leaf such as is shown in fig. 33. Sometimes the last remaining tooth may be quite close to the leaf-base. Although I have not as yet seen gradations between leaves such as those in fig. 33 and adult leaves, yet I think the above shows fairly conclusively that the latter are reduced leaf-blades, quite sessile, and with a very wide leaf-base, and that there is no reason to think them to be phyllodes.
If we look upon the juvenile plant as the ancestral form, it seems very clear that this latter must have been an inhabitant of a region with a moist and equable climate, whose conditions we can imitate in some degree by bell-glass culture. The plant mentioned and figured in a previous paper† has been kept continuously under a bell-glass since the date mentioned—February, 1899—and is now—November, 1900—17.8 cm. tall, and its thickest branch 4.75 mm. in diameter. The central portion of its three main branches are almost naked for a distance of 3.7 cm., but the lower third of the whole plant is one mass of very healthy green leafy shoots, the largest of which are 3.5 cm. in length, and the whole of whose leaves are of the deeply toothed almost pinnatifid
[Footnote] * l.c., p. 280.
[Footnote] † l.c., p. 396 and pl. xxix. For photograph of adult shoot see pl. xxviii.
juvenile type. In several places, even at a height of 10 cm. above the soil, adventitious roots have been developed, the longest of which is 13 mm.; but in every case as yet such have after a time withered at the apex, and in no instance have reached the soil.
I have never seen V. armstrongii in the wild state; it is probably a rare and local plant, occurring in the southern portions of the Canterbury Alps. Mr. T. Kirk's record of its occurrence in Nelson, Westland, and Otago* requires confirmation. The common whipcord Veronica of northern Canterbury and of southern Nelson is V. lycopodioides.† As to the Westland habitat, it is improbable that there are any Veronicas of the above-named type in that region. In my garden our plant still keeps its xerophytic structure, nor while growing in the open air has any part ever reverted to the seedling form. It also flowers freely year by year, and differs little, I should imagine, from the typical alpine form.
No. 844. Rubus cissoides, A. Cunn., var. pauperatus, T. Kirk. Plate XII., figs. 39, 40, 42, 43, 44, 45.
The seed was collected by Mr. F. Anson at Piraki, Banks Peninsula, from a plant growing as a liane just outside the forest. This plant was leafy in its upper part, but almost leafless elsewhere. Sown on the 1st September, 1899, one seed germinated on the 20th November, 1899, two more plants appeared by the end of the same month, while a fourth seed did not germinate until the 20th August, 1900—i.e., till nearly a year from the date of sowing. So far as observed the seedlings grow at first with considerable rapidity. By the 2nd December, 1899, the oldest seedling was 10 mm. tall, with the 1st foliage leaf in process of development but not unfolded. By the 19th June, 1900, its height was 1.5 cm., And there were six leaves fully developed, while by the 1st November, 1900, there were nine leaves almost fully developed, and it had increased 6 mm. in height. It will be noted that the stem-growth is very slow, its length at this point being exceeded by that of several of the petioles.
Description of Seedling.
Primary root (in plant with 1st leaf at an early stage of development) 14 mm. long, white, fleshy, stout, with very few lateral rootlets.
[Footnote] * l.c., p. 521.
[Footnote] † I am referring to the plant usually so named by botanists in New Zealand; whether it be Hooker's species is another matter. The plant in question is especially abundant on some parts of Peveril Peak, Canterbury, where it forms quite a large proportion of the subalpine scrub.
Hypocotyl 5 mm. long, terete, thickest at base, pinkish, especially towards cotyledons.
Cotyledons oblong, petiolate, bright-green or purplish-red throughout, obtuse, entire, with margin ciliated with glandular hairs; lamina 4mm. × 3mm., horizontal, bent almost at right angles to the nearly vertical petiole; petiole 1.15 mm. long, semi-erect or nearly vertical, channelled on upper surface, connate and slightly swollen at base.
Plant with nine leaves: Remains of cotyledons and 1st leaf show the lowest leaf to be the second.
2nd leaf (fig. 39) 5.5 mm. × 3.25 mm., ovate in outline, bright reddish-purple on both surfaces, coarsely and deeply toothed so as to be almost pinnatifid or lobed, and each tooth ending in a swollen apiculus, ciliated and sparsely hairy on both surfaces with simple and also with glandular hairs; midrib swollen on under-surface of leaf; petiole half the length of lamina, channelled above.
3rd leaf 6 mm. × 3.75 mm., similar in other respects to 2nd leaf.
4th leaf 12 mm. × 5 mm., very similar in all other respects to 2nd leaf, but with four teeth on one side and three on the other; lamina 7.5 mm. × 5 mm.; petiole 5 mm. long.
5th leaf similar to 4th leaf, but with longer petiole.
6th leaf lanceolate, horizontal, with apex sloping towards ground, subtruncate at base, 5-toothed on each side; lamina 10 mm. × 6 mm.; petiole 8 mm. long, sheathing at base, deeply and narrowly channelled down upper surface, inserted on stem at angle of 45°; edge of channel very thick.
8th leaf lanceolate, subcordate, very dark-purple, almost black on upper surface, much paler and rather grey beneath, irregular and deeply serrate; lamina 2.12 cm. × 8.3 mm.; petiole 3.2 cm. long; margin ciliated with long white and also with glandular hairs, sheathing at base; midrib, veins, and swollen apiculi of teeth pink.
9th leaf (in process of development): Lamina almost opened out, 12 mm. × 3 mm.; petiole 2.4 cm., with two prickles.
Stipules inserted at upper end of sheath, linear or almost filiform, ciliated, often bent downwards.
Stem of slow development, partly enclosed by sheathing leaf-bases; internodes 1 mm. long or a little more.
From the above description it will be seen that there are two distinct forms of seedling leaves, the first ovate or cordate-ovate, with a very deeply cut lamina and petioles shorter or only a little longer than the lamina; the second lanceolate or narrow-lanceolate, extremely dark in colour, not so deeply toothed as the first, type of seedling leaf, but of much greater size and with the petiole always longer than the lamina.
The first seedling leaf-form much resembles the early seedling leaf of Rubus australis, var. glaber, whereas the second form is like the reduced lamina of an adult leaf (cf. figs. 40 and 44).
The difference in appearance between R. cissoides when a liane of the forest and when it forms a round mass of intertwining branches and midribs in the open is quite as striking as that of Pittosporum rigidum, described earlier in this paper; but there is this great difference: that the forest form of Pittosporum rigidum is the early seedling form still maintained, whereas the forest form of the Rubus in question more resembles the second seedling stage of the latter. In both, however, the form in the open is a direct adaptation to xerophytic conditions, though whether this form is hereditary in our plant I am not in a position to determine. This in large measure arises from the fact that, so far as I know, the extreme xerophilous form has never been observed in flower or in fruit. In order to verify my own observations I wrote to Messrs. T. F. Cheeseman and D. Petrie,* inquiring if they had ever seen this particular form of the plant in fruit, &c., and both these botanists, of most wide experience with regard to New Zealand plants, replied that they had never seen the almost leafless form in flower or fruit. Mr. Cheeseman qualified his information with the remark that he saw no reason why it should not flower. That is indeed very true, since poor soil, as every observant gardener knows, causes early flowering, while, on the other hand, it is a proved physiological fact that a moist atmosphere will hinder the development of the reproductive organs in plants.† Here, then, is quite a case to the contrary: the plant of the moist wood produces fruit regularly, the plant of the barren wind-swept slope rarely or never does so.
The forest liane climbs over tall shrubs or low-growing trees. It is well furnished with leaves, which are pinnately trifoliate, with the leaflets equal in size, or the terminal one is often the largest. The margin varies from coarsely and deeply toothed (fig. 42) to merely waved. The leaf-surface is usually bright-green and shiny, and always quite glabrous. The leaflets are from broad to narrow lanceolate in shape, rounded at the base, and articulated to the usually rather long channelled petiolule, that of the terminal leaflet being much the longer. Petioles, petiolules, and midribs may be quite unarmed in the most extreme cases, or furnished with few or many pale-coloured prickles. Such leaves may measure
[Footnote] * Mr. S.D. Barker also informs me he has never seen flowers, &c., on this plant.
[Footnote] † Schimper, A. F. W., “Pflanzen-Geographie,” Jena, 1898, pp. 30, 31.
± 17 cm. in length, with leaflets 6.5 cm. × 15 mm., or the leaflets may be broader or more narrow.
When the plant is growing in the open we find a very different state of affairs. Then very often the leaf-blades are entirely wanting, and the leaf consists only of very long and prickly midribs. Often, however, there is a very small lamina at the apex of the midrib (figs. 43, 44, 45), especially in parts of the plant which are most sheltered. Such laminæ offer every gradation in size according to their position with regard to excessive light, wind, &c., between large ones such as described above and those of 2 cm. × 3 mm., or even of much smaller size. On the midribs are many more prickles than on those of the forest liane. These prickles are usually from two to four in number, close together, and situated on the under-surface and sides of the midrib, but never on the stem, each prickle measuring about 2 mm. to 2.25 mm. in length, and with a stout base 3 mm. or more long. They are of a straw-yellow colour, straight or curved, and so numerous as, with their peculiar colour, to give a distinct character to the plant.
The plant itself growing in these dry situations—volcanic hills, river-terraces, &c.—forms a round mass of intertwining, long, flexible shoots, having often a height of 61 cm., with a diameter of 84 cm., or the dimensions may be very much greater. So elastic is such a bush that when one treads hard down upon it the twigs spring back at once into their former position. This elasticity is exhibited at quite an early age in seedling stems and petioles. From out of the round twiggy mass of the plant erect shoots often arise, quite tender and soft, and with rudimentary leaves. Such are usually killed at a very early stage by the wind and sun. This destruction of the growing-point of the young shoots may account for the non-flowering of the plant, for flower-buds may not develope properly in the dense parts of the twiggy mass, and when exposed to the external climatic conditions are too tender, and so destroyed. In many instances the above-mentioned leaves bend down into the plant for shelter. On this account the lateral leaflets are often bent downwards at an angle to the midrib, which tends to fasten the twigs together, and so to consolidate the whole mass of the plant.
Several other species of Rubus in New Zealand have the habit of this plant when growing under xerophytic conditions, so assuming the form of shrubs rather than of lianes. Indeed, it is quite easy to see how from such a manner of life, where the climbing habit, suited as it is only for very special conditions, is no longer possible, a shrub could be evolved from a. *
[Footnote] * “Beiträge zur Biologie der Lianen,” Jena, 1892, pp. 60, 162.
liane, as described by Schenk* and Warming, and I think we may safely conclude with Diels* that a number of our xerophilous shrubs have thus descended from forest plants, and in certain cases from lianes.
The prickles are developed to a much greater extent in the xerophilous than in the hygrophilous form of our plant, although they are clearly an adaptation for climbing, as was first shown by Kerner.† Afterwards, in the xerophyte, they become of still greater use by binding into a wind-resisting whole the numerous branches. The fallaciousness of Wallace's ‡ idea that such prickles were a protection against snails has been ably exposed by Mr. G. M. Thomson.§ In the seedling the prickles did not appear until quite late (the 8th leaf) in its development; but in the xerophilous form they increase to a great extent, the conditions of its existence being seemingly better suited for their appearance than are those more sunless and damper ones to which the liane is exposed.
No. 768. Ligusticum filifolium, Hook. f. Plate XII., figs. 38, 41.
The seed was collected on Jack's Pass, Hanmer Plains district, at beginning of February, 1899. It was sown, on the 6th September, 1899, and germinated on the 1st August, 1900. The young plants continued to make their appearance until the middle of September, 1900.
Description of Seedling.
Early development: The cotyledons remain within the seed-coat, and still surrounded by the walls of the mericarp, absorbing nutriment until they are pulled out of the ground and out of the pericarp by the lengthening of the hypocotyl, and of their own peduncles more especially. Within the seedcoat their upper flat surfaces are pressed together, absorbing nutriment especially with their apices. Emerging from the soil in a low arch, the short hypocotyl has become stout, and offers good support for the petioles to pull their leaf-blades out of their coverings. The cotyledons are at first very narrow, with their laminæ green, flat, and a little broader than the longer filiform petioles, which are of reddish colour, faintly channelled above and swollen at the base. At this stage the cotyledons are sometimes bent or twisted. By the time the cotyledons have reached a size of (laminæ) 19mm. × 2mm., and petioles 16 mm. in length, these latter have spread out
[Footnote] * l.c., p. 247.
[Footnote] † “Pflanzenleben,” Leipzig, 1887, p. 637. Here a figure of the reduced leaves is giver, the plant being designated Rubus squarrosus.
[Footnote] ‡ “Darwinism,” London and New York, 1889, 2nd ed., p. 433.
[Footnote] § “Nature,” vol. 42, 1890, p. 222.
laterally, and are at junction of lamina 10 mm. apart. At this stage from between the cotyledons the 1st leaf is in course of development, not erect, but arching laterally, and with the two side leaflets closely pressed together, near its apex. Following the development of the leaf, the petiole grows much more rapidly than the lamina. This at a very early stage of development is about the same length as the petiole, its lateral leaflets pressed closely together. As development proceeds and the petiole lengthens it becomes curved at its upper end, often forming an arch, the lamina being bent inwards and downwards like the numeral “2” (fig. 38), and with the apex of its terminal leaflet approached more or less near to the base of the petiole. Growth, proceeding, the petiole gradually straightens, until by the time the lamina has expanded it is quite straight. After growth of forty-four days the cotyledons attained a length (including petiole) of 3.6 cm., and the 1st leaf a length of 2.31cm., with lamina 6 mm. and petiole 2.25 cm. While this development of cotyledons and leaf is proceeding, the root, in an early stage pale and translucent, has now become a deeply descending thick tap-root containing an abundance of food-material, which has been here stored up at the expense of rapid growth and development of stem and leaves. After about two and a half months' growth the roots are out of the bottom of the pot, 9.2 cm. in depth, in which the seed was sown, and are from 1 mm. to 1.5 mm. in diameter above. The 2nd leaf issues from the protecting sheath at the base of the 1st leaf, and undergoes the same process of development as the 1st leaf.
Root very long and tapering, finally extremely thick and stout, with numerous lateral rootlets.
Hypocotyl 3 mm. above ground in largest plants, short, stout, glabrous, very pale yellowish-green, often stained with purple.
Cotyledons linear or extremely narrow linear-lanceolate, sometimes falcate, green on both surfaces, entire, subacute or obtuse, glabrous, ± 4.5 cm. in length, with lamina tapering into and about equalling petiole; lamina 2mm. broad; petiole brownish or brownish-red, very obscurely channelled, connate, and forming a short sheath at base.
1st and 2nd leaves radical, ± 4.8 cm. long, ternate or palmately trifid, glabrous, green on both surfaces or sometimes stained purple; leaflets and segments narrow-obovate, lanceolate or linear-lanceolate, entire or with from one to three teeth at apical end, 14 mm. × 5 mm. or of considerably smaller size, acute, 1-nerved.
Ligusticum filifolium grows on shingle-slips, usually on such as occur in the dry lower mountain region of the South Island of New Zealand, although specimens may be occasion-
ally met with on the alpine shingle-slips at an altitude of 1,200 m. It is also found in the shade of the small patches of Fagus cliffortioides so often met with on the slopes of river-terraces.
The adult leaves are usually divided into segments very much narrower than those of the seedling. There are, however, certainly two forms of this plant so far as the leaves are concerned, the one with quite filiform leaves and the other with the leaf-segments 12 mm. × 3 mm., or even broader. The form, growing under the shade of the beech-trees has usually the leaf-segments broader than the form of the open. As to what the effect of shade is on the narrow-leaved form. I cannot yet state. Moreover, the broad-and narrow-leaved forms may be two separate species. The rapid development of the root in thickness is of great benefit to the young plant. Possibly, too, the slow germination of the seeds may have an œcological meaning.
Explanation Of Plates X–XII.
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|Fig. 1.||Seedling leaf of Pittosporum rigidum, closely approaching the adult xerophilous leaf form; × 4.|
|Fig. 2.||Early seedling leaf form of Pittosporum rigidum; × 4.|
|Fig. 3.||Leaf of seedling Pittosporum rigidum, resembling fig. 1 above and fig. 2 below; × 4.|
|Fig. 4.||Early seedling leaf of Stellaria roughii; × 6.|
|Fig. 5.||Cotyledon of Gaya ribifolia.|
|Fig. 6.||Early seedling leaf of Gaya ribifolia.|
|Fig. 7.||Seedling of Gaya ribifolia. with cotyledons and 1st leaf.|
|Fig. 8.||Early seedling leaf of Gaya ribifolia.|
|Fig. 9.||Later seedling leaf of Gaya ribifolia.|
|Fig. 10.||Leaf from one-year-old plant of Gaya ribifolia.|
|Fig. 11.||Seedling plant of Plagianthus betulinus; early leaves have fallen off.|
|Fig. 12.||Leaf from young plant of Plagianthus betulinus.|
|Fig. 13.||Leaf from semi-shrubby form of Plagianthus betulinus.|
|Fig. 14.||Leaf from young plant of Plagianthus betulinus.|
|Fig. 15.||Leaf from semi-shrubby form of Plagianthus betulinus.|
|Fig. 16.||Seedling of Plagianthus betulinus, Chatham Island var., showing cotyledons, hypocotyl, and primary root.|
|Fig. 17.||Early seedling leaf of Plagianthus betulinus, Chatham Island var.|
|Fig. 18.||Leaf from young plant of Plagianthus betulinus, Chatham Island var.|
|Fig. 19.||Leaves from young plant of Plagianthus betulinus, Chatham Island var.|
|Fig. 21.||1st seedling leaf of Veronica odora; × 4.|
|Fig. 22.||2nd seedling leaf of Veronica odora; × 4.|
|Fig. 23.||3rd seedling leaf of Veronica odora; × 4.|
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|Fig. 24.||Later seedling leaf of Veronica odora, of Maungatua.|
|Fig. 25.||8th seedling leaf of Veronica odora; × 4.|
|Fig. 26.||Much-toothed leaf of Veronica odora; × 4.|
|Fig. 27.||Early seedling leaves of Veronica armstrongii; × 6.|
|Fig. 30.||Entire and rather anomalous seedling leaf of Veronica armstrongii; × 6.|
|Fig. 31.||Later seedling leaves of Veronica armstrongii, showing transition between typical seedling and adult leaves; × 6.|
|Fig. 35.||Very deeply cut seedling leaf of Veronica armstrongii; × 6.|
|Fig. 36.||2nd seedling leaf of Veronica squalida; × 4.|
|Fig. 37.||3rd seedling leaf of Veronica squalida; × 4.|
|Fig. 38.||Seedling of Ligusticum filifolium, with cotyledons and 1st two leaves.|
|Fig. 39.||2nd seedling leaf of Rubus cissoides, var. pauperatus; × 4.|
|Fig. 40.||8th seedling leaf of Rubus cissoides, var. pauperatus.|
|Fig. 41.||Early seedling form of Ligusticum filifolium, showing 1st leaf in process of development.|
|Fig. 42.||Adult leaf of Rubus cissoides, var. pauperatus, as found on liane form, or in sheltered portion of xerophilous form.|
|Fig. 43.||Reduced leaf-blades of Rubus cissoides, var. pauperatus.|
|Fig. 46.||Stellate hair from leaf of Gaya ribifolia.|