5. Pleurophyllum Meadow.
Beyond learning that a certain, number of most striking and beautiful herbaceous plants grow in company with one
another there, there is little to be found in the writings of those botanists who treat of the Southern Islands, as to the extent, limits, altitude, or edaphic conditions of the plant-formation which these plants constitute, or whether, indeed, such plants do form a distinct society. From the writings of Sir Joseph Hooker it seems clear that at the northern end of Auckland Island—that part alone of the group where his botanical explorations were made—a considerable altitude must be reached before the above-mentioned striking plants are encountered in any number, while he distinctly points out that on Campbell Island, owing to their occurrence at a lower altitude, they form a more striking feature of the landscape. Thus, Hooker writes, “Beyond the wooded region some of the same plants” [the forest trees] “in a dwarf state mingled with others compose a broad shrubby belt, which ascends the hills to an altitude of 800 ft. or 900 ft., gradually opening out into grassy elopes, and succeeded by the alpine vegetation. It is especially towards the summits of the hills that the most striking plants are found, vying in brightness of colour with the arctic flora, and unrivalled in beauty by those of any other antarctic country.”
On Adams Island, as mentioned before, strips of treeless hillside reaching to the edge of the water alternate with strips of rata forest. Now, it is just on these treeless pieces of hillside that the formation under consideration appears in that part of the Auckland Group, and so rich in striking flowers is the piece of land at the western extremity of Carnley Harbour that it has received the name of “Fairchild's Garden,” a tribute to the memory of the late John Fairchild, who, as captain of the “Hinemoa,” did much to advance the knowledge of New Zealand natural history.
The following are the most important members of the Pleurophyllwn formation: Pleurophyllum speciosum, Pleur. criniferum, Celmisia vernicosa, Cotula plumosa, Cot. propinqua (Compositœ); Ligusticum (Aciphylla) latifohum, Lig. (Aciph.). antipodunt (Umbelhferes); Nertera depressa(Rubiaceœ); Epilobium confertifolium (Onagraceœ); Stilbocarpa polaris (Araliaceœ); Acœna sanguisorbœ var. antarctica (Rosaceœ); Myosotis capitata (Boraginaceœ); Gentiana concinna, Gent. cerina (Gentianaceœ); Bulbinella rossii (Liliaceœ); Scirpus aucklandicus (Cyperaceœ); Aspidium vestitum, Asplenium obtusatum (Filices); various mosses, liverworts, and lichens. In the gullies is a good deal of Veronica elliptica.
Between the Pleurophyllum meadow and the stony beach comes a zone of Poa foliosa, the before-mentioned tussock-grass with great “trunks,” Carex trifida, and alternating with these, or in close proximity to them, Stilbocarpa polaris and Ligusticum latifolium. Probably the Pleurophyllum forma-
tion contains some of the smaller grasses, but in midwinter identification of these was impossible.
The soil of this formation consists of a great depth of peat, which at the time of my visit was very wet and sticky, but certainly not so wet as I had expected. The ground, in fact, is neither bog nor even semi-bog, but merely a very moist peaty slope. The forming of peat, even while a plant is alive, is a common-enough occurrence amongst New Zealand cushion-plants. Kirk shows, for instance, how the dense lower leaves on Raoulia goyeni of Stewart Island become changed into peat while the upper leaves are performing their usual functions (62, p. 215). In Fuegia also the leaves of living plants are rapidly converted into peat. Darwin writes regarding Astelia pumila (23a, p. 286), “Fresh” leaves are always succeeding one to the other round the central taproot; the lower ones soon decay, and. in tracing a root downwards in the peat the leaves yet holding their place can be observed passing through every stage of decomposition till the whole becomes blended in one confused mass.” In the Southern Islands such peat-forming is very plainly to be seen, especially in winter, in certain of the plants, which die down to the ground. Then the leaves of the past year lie rotting upon the surface of the soil, while their bases form great decayed masses many centimeters in thickness round the leaf-bases of the young leaves of Pleurophyllum criniferum or P. hookeri. In these sheaths of decaying leaves considerable numbers of earthworms are found, and they appear also to be fairly numerous in the peat itself. This will lead to a greater amount of oxygen in the soil than is usually present in peat, and probably there is a considerably less percentage of humic acids; but I have no data on this head. All that can be said is that, notwithstanding the soil is altogether peat, it must be very much more favourable for plant-life than is the peat of an ordinary bog, or even a dry heath.
Since my visit took place in the depth of winter I myself can say nothing regarding the magnificent display of flowers which this spot and the formation in general, if it be indeed a true formation, exhibits during the summer season. However, Chapman gives a most vivid picture of Fairchild's Garden, which is here quoted almost in its entirety: “This place” (16, p. 505) “will now be known, by the name we gave it—Fairchild's Garden. It extends from the strait at the north-west end of the island along the shore to the first piece of bush, and thence up to and over the summit of the hill—in all perhaps 400 acres—one of the most wonderful natural gardens the extratropical world can show. No doubt other parts of Adams Island and other places in the group are equally beautiful, but the day we spent here can never be for-
gotten. A peaked rock overhead is 700 ft. above the sea; the summit rocks are 1,100 ft. by the aneroid. The whole of the ground up to these and beyond them is literally packed with beautiful flowering herbaceous plants. Near the shore the Ligusticums, L. latifolium and L. antipodum, grow in splendid profusion, their stout rhizomes and huge rigid leaves stopping the progress of pedestrians. Along the shore were masses of golden lily (Anthericum rossii) in seed. Here, too, grew sweet-scented Cotula lanata and its handsome congener C. plumosa, both of which are worth cultivating. Over the whole country Pleurophyllum speciosum sends up, among huge ribbed leaves 2 ft. long, its spikes of beautiful lilac or purple flowers. These spikes are usually four or five, sometimes eight or ten, in number. The regular imbricating of the large ribbed leaves, so strong as to push aside the rank grasses, renders these plants singularly beautiful. They form deep cups of crisp foliage, which gives way with a crash as you set foot on it.” “The next species, Pleurophyllum criniferum, was also plentiful. Its leaves are even larger, and, although not so handsome, make it a fine plant, especially as its tall white flower-stalk, sometimes 3 ft. high, covered with button-like brown rayless flower-heads 1 in. across, is a very striking object.” “Here, too, we met in immense quantities the most beautiful of all the Celmisias, C. vernicosa, a little plant with leaves here seldom more than 2 in. long, gleaming like polished nephrite new from the lapidaries' hands, arranged in the most perfect rosettes.”
In the middle of winter the Pleurophyllum meadow presents a very different aspect, owing perhaps not so much to the absence of flowers as to the winter habit of some of the more important plants. Thus, the huge leaves of Pleurophyllum criniferum are altogether wanting, P. speciosum only forms comparatively small rosettes—one's feet do not then “crash through the horizontal leaves as though walking on thin ice” (56, p. 220)—while Bulbinella is hardly visible at all, the winter buds hidden by the brown bases of the old decayed leaves just protruding above the surface of the ground. To be sure, the great rounded leaves of Stilbocarpa polaris and the large dark-green leathery pinnate leaves of Ligusticum latifolium still form as dense masses of greenery as in summer, but here the absence of the inflorescence—as large as the head of a man, according to Hooker (46, p. 16)—must make a striking difference between the winter and the summer aspect; but as these plants appear frequently to form an association mixed with little other vegetation of a striking appearance they exercise much influence on the winter physiognomy of the meadow as a whole. Everywhere the ground is dotted with the bright-green winter rosettes of Pleurophyllum speciosum
pressed closely against the ground, or numbers of such occur in close proximity. Such rosettes seem to vary considerably in size according to their position with regard to wind and light, those of shady gullies being much larger than those on the hillside. A rosette in the open may be ± 25 cm. in diameter, made up of quite a few leaves, hugging the soil, pressed closely above one another and arching downwards so that their upper surface is convex, a kind of cup being thus formed, with the highest part of its arching leaves as its brim. 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 (27, p. 291). Very frequent all over the formation are large colonies of Bulbinella rossii, the green tips of the winter buds just visible above the dark-coloured peat, or the buds are completely hidden by the brown leaf-bases of the previous year's leaves. Such colonies may be several square metres in extent. Trailing over the surface of the ground very abundantly are the long shoots of Acœna sangutsorbœ antarctica, with its characteristic pale-green leaves almost or quite glabrous on the upper surface. The small-leaved bright-green Nertera depressa, another creeping-plant, is also very abundant. Here and there are grass-like tufts of Scirpus aucklandicus and the silvery-leaved Helichrysum prostratum, and very frequently associated with these are the shining green winter rosettes of Gentiana cerina. The feathery leaves of Cotula plumosa are especially noticeable, its thick green stems straggling over large patches of ground. Near the sea Lomaria dura is a frequent member of the formation.
Turning now to the life-forms of the endemic members of the Pleurophyllum meadow, the most striking feature, and that which distinguishes it especially from the subalpine and alpine meadows of the New Zealand Alps, is the very large leaf-surface possessed by some of the most characteristic plants. Similar leaf-development is seen, however, in some other parts of the New Zealand biological area. In Stewart Island and some of the adjacent islands is Aralia lyallii, and in the Chatham Islands the magnificent Myosotidium nobile, now almost extinct in the wild state (23, p. 302). In Kerguelen Island also Pringlea antiscorbutica may be instanced as a parallel development under similar conditions.
Pleurophyllum speciosum has large leaves pressed close to the ground, and forming, according to Kirk, “a flat rosette 3 ft. to 4 ft. in diameter” (56, p. 220). This position of the leaves must be of great advantage in enabling the plant to
resist the wind, and at the same time it prevents the encroachment of other plants. The winter rosettes, as shown above, are much smaller—25 cm., or about 10 in., in diameter. The leaves have white sheathing bases, which in the largest—i.e., the outermost—measure ± 6 cm. long × ± 7 cm. in breadth, and are densely clothed with long silky hairs pressed closely against the surface. The lamina of such a leaf measures 14 cm. × 14 cm. On its under-surface are about twenty-five very prominent, stout, firm ribs forming the boundaries of channels ± 3 mm. in breadth, filled with a loose tomentum These channels gradually narrow towards the leaf-base, and are widest above, measuring in one leaf measured 9 mm. The upper surface of the leaf is much channelled with parallel channels, triangular in cross-section and ± 9 mm. wide from ridge to ridge. On the ridges are many transparent moniliform hairs which stretch over the channels. The general aspect of the leaf, so far as its ridges and channels are concerned, is that of the corrugated iron so much used in roofing in New Zealand, and this corrugated appearance must be still more striking in adult leaves. Within the excellent protection afforded by the leaf-sheaths are the bright pale-yellow leaves of the young bud. A cross-section of the leaf shows a thin-walled epidermis, with the outer wall hardly thicker than the inner ones. Beneath this is a one- or, in places, a two-layered large-celled water tissue. The palisade parenchyma consists of rather short, oblong cells, and the spongy parenchyma is extremely loose, the intercellular spaces being of very large size. The roots are large and fleshy, but my notes say nothing as to their direction in the soil.
As for Pleurophyllum criniferum, I did not note it at all on either Auckland or Campbell Island, owing to its habit of dying completely to the ground in winter, the tips of the buds alone just projecting above the surface; nor was it until digging in the bogs of Antipodes Island that I met with this, to all accounts, very common plant. The young bud is closely surrounded by a very thick covering of old leaf-bases in various stages of decay. Kirk describes the adult plant as of a very different habit from P. speciosum: “The leaves are usually petioled, and from 1 ½ ft. to 3 ft. in length, suberect and spreading, forming a ring round the erect scapes” (56, p. 220). In texture they are “membranous, but firm, white with thin tomentum beneath” (58, p. 434). Hooker speaks of this plant “as so bulky that an ordinary specimen weighs many pounds” (46, p. 33), and from this latter it may be seen how great a peat-maker this species must be.
Bulbinella rossii, which in summer has numerous thick, spreading, broad leaves 40 cm. long × 3.5 cm. broad, in winter,
as before stated, exhibits merely the tips of the buds, which reach above the surface of the ground to a height of ± 3.5 cm. Such buds, from certain examples measured, are about 11 cm. in length × 2.26 cm. in diameter. They are somewhat conical in shape, and quite sharp at the apex, thus easily piercing the soil. Above they are pale-green, but gradually toning down to, yellowish-green or very pale-yellow at the base. The leaves of the bud are fleshy and imbricate closely, thus protecting the interior of the bud, while the bud itself is protected by a thick covering of the dead bases of the old leaves, consisting mainly of the vascular bundles. The rhizome measures probably 2 cm. or so in thickness, and is concealed by the dense masses of thick and fleshy yellow roots, which usually radiate outwards and downwards from the base of the bud.
Stilbocarpa polaris is a noble plant, somewhat after the manner of the Chilian Gunnera chilensis. The large rhizome, measuring ± 8 cm. × ± 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 × 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, which seem to vary considerably in number in various individuals. Drops of water frequently accumulate on these hairs, but whether they can absorb such, as seems to me likely, can only be ascertained by experiment. These hairs remain unchanged in number in plants cultivated under conditions quite different to those of their natural habitat, judging from a plant I have had in cultivation several years in the neighbourhood of New Brighton, on a sandhill at the back, of a wall, sheltered from the north-west, and about 1m. from a small stream of water. The leaf-anatomy of Stilbocarpa is of some interest. The epidermis on the under-surface of the leaf is attached only to the veins, thus leading to numerous spaces full of air between epidermis and spongy parenchyma. At first there seems to be an almost colourless tissue of rounded cells between the epidermis and palisade, but evidently these become ruptured and the above-
mentioned air - spaces are formed. The lower epidermis contains large numbers of stomata. The upper epidermis consists of a single row of large rectangular cells which are slightly cuticularised. The assimilating portion of the leaf consists of about six rows of palisade parenchyma, each call about twice as long as broad, succeeded by the smaller and rounder cells of the spongy parenchyma, the lowermost of which project into the above-mentioned airspaces somewhat after the manner of the assimilating tissue in the air-cavities of Marchantia.
Ligusticum latifolium has leaves ± 60 cm, in length, with a very thick stalk ± 2 5 cm. in diameter. The blade is dark-green in colour, very coriaceous, ovate in outline, and bipinnately divided into rather broad segments, which are 3- to 5-lobed, each lobe terminating in a needle-like sharp point. These lateral segments are not flat, but bent inwards, thus bringing the two surfaces into proximity, and the upper half into a vertical position with regard to the light. There are fine Ligusticums in both the subalpine region of New Zealand and the moist coastal regions of the South Island, but, as is the case with these Southern Island plants, they nearly always exceed their largest New Zealand representatives in luxuriance of growth. The leaf-anatomy much resembles that of L. antipodum, described below, but the stereome of the under-surface is replaced by water tissue, and the spongy parenchyma in the middle of the leaf does not seem quite so open as in the allied species. A specimen which I have bad in cultivation for some years side by side with Stilbocarpa polaris, as mentioned above, has decidedly thinner leaves than those of plants recently collected on Auckland Island.
Liqusticum antipodum is a rather smaller plant than Lig. latifolium, and the leaf-blade is cut into a great number of narrow linear needle-like segments, the ultimate ones being ± 2 cm. long. The leaves of this plant are in part dealt with when treating of the subalpine rocks of Campbell Island There is a thick cuticle on both surfaces. Next to the epidermis is a ring of stereome, which stretches into the interior of the leaf, alternating with broad layers of palisade parenchyma. The arrangement on the under-surface is much the same, but the green tissue is composed of rounded cells. In the centre of the leaf is spongy parenchyma with large intercellular spaces. There are a number of resin-passages Stomata occur on both surfaces, and they are sunken.
Myosotis capitata, although not endemic in the Southern Islands, is by no means a common plant in New Zealand. In winter it presents semi-rosettes of rather thick, soft, dark-green leaves ± 5.3 cm. × ± 6 mm., covered on the upper
surface with bristly white hairs. The stems, ± 6 mm. in diameter, 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 semi-patent, and frequently recurved at their extremities, and dense enough for one rosette to touch the next. A cross-section of a leaf shows that it is dorsi-ventral, with a. non-cuticularised epidermis and large intercellular spaces in the spongy parenchyma.
Gentiana cerina has in winter rather dense rosettes, crowded together, of dark-green imbricating leaves, the four or five outer leaves much larger than those crowded internally. Bach rosette is about 3.7 cm. in diameter. Such a plant may measure 10 cm. × 8 cm. In spring the rosettes open out and the new branches spread out radially, with their tips ascending.
Cotula plumosa, which is also found in Kerguelen Land, has stout creeping stems 9 mm. in diameter, by which it spreads over the surface of the ground. They are green on the upper but paler on the under surface, and strongly marked with old leaf-scars, the internodes being ± 1.5 cm. long. Rather stout, cord-like roots, furnished with filiform lateral rootlets, are given off from the nodes. Such creeping stems may be quite without leaves for long distances, and serve both as storage and assimilating organs; in a collected plant 25 cm. were quite bare, but no measurements were taken from growing plants. The leaves in winter are in rosettes at the ends of the creeping stems. The very young leaves in the centre of each rosette are protected by a covering of long silky hairs. The leaves have broad sheathing bases, fleshy in the centre and membranous at the margin, tightly overlapping one another, and this further protects the bud. In each winter rosette there are only a few fully developed leaves. These are pinnate, with the pinnæ much divided, the whole leaf having a feathery appearance, as the specific name implies. The upper side of the leaflet-axis is furnished with about 7 segments—there are, in fact, segments from base to apex; but the lower side has segments only near, the apex. The segments also are only divided on their outer side. By this arrangement the various portions of the lamina hardly overlap at all. There is also a gradual transition from pinnæ without any lower segments to those with 2–3 segments on the lower side, the two nearest the base having no lower segments. Such a leaf as the above measures 14.2 cm.; the lamina 7.5 cm. × 4.3 cm.; the pinnæ 1.8cm. × 10mm. The sheath is 3.5cm. long × 5.5 cm. wide (when spread out). The remainder of the petiole is stout, almost flat on the upper and rounded on the under surface,
tapering slightly from below upwards, and 2 5 mm. thick × 5 cm. broad towards its centre. The leaves are pale-green in colour. On the blade and sheath are a few straggling hairs. Numerous roots are given off from the leafy portion of the plant, but only a few from the naked creeping stems, and these roots will function especially as holdfasts. Cotula propinqua is intermediate between the above and Cot. lanata, so need not be further dealt with here.
Celmisia vernicosa has the leaves in densely crowded rosettes 3.1 cm. in diameter in one case measured; but they must very frequently be much larger than this, for the leaves, according to Hooker (47, p. 136), may reach the length of 4 in. (10.1 cm.). Below are the remains of many dead leaves. The leaves are bright-green, highly polished and shining, extremely coriaceous, and with margins recurved. The rosettes frequently form large patches. Veronica benthami is described in she part relating to Campbell Island. The remaining plants (spermaphytes and pteridophytes) of this formation are more or less common in New Zealand, and need not be dealt with here.
Perhaps that which is most noticeable about the Pleurophyllum meadow when comparing it with related ecological formations in New Zealand—as, for instance, a western sub-alpine meadow in the South Island—is the very different colouring of the flowers. In the subalpine meadow is the dazzling white of Ranunculus lyallii or the various species of Celmisia, the yellow-throated but otherwise white Ourisia macrocarpa, white gentians, white Ligusticums, the yellow-, white-, or cream-coloured Senecio scorzonerioides, and amongst the shrubs are white-flowered Olearias and Veronicas (these sometimes with a shade of lilac) and yellow Senecios; in short, with hardly an exception, all amongst flowers in any way conspicuons are white or yellow.* In the Pleurophyllum meadow, on the contrary, are: P. speciosum, with disc-florets purple and ray-florets purplish-white; P. criniferum, with flower-heads deep-brown; Lig. latifolium, with large umbels of reddish flowers; Lig. antipodum of similar colour to its ally; Celmisia vernicosa, with rays white and disc-florets deep-purple; Bulbinella rossii, orange-coloured; Veronica benthami, deep-blue; Gentiana cerina, white with stripes of bright-red; Myosotis capitata, violet-blue fading to purple; Epilobium confertifolium, pink Moreover—and this is a very significant fact—with the exception of the Myosotis, a, rare plant in New Zealand, the whole of the above are endemic, and they are also the dominant plants
[Footnote] * The alpine flora of Australia, as evidenced by the plants of Mount Kosciusco, have, according to Mr. J. H. Maiden, “an enormous preponderance of white flowers,” while yellow flowers come next in number (75a, p. 29).
of the formation. Certainly there ate some yellow flowers; e.g., Cotula plumosa and perhaps Bulbinella rossii should be here included. The gentian is described by Kirk as occasionally white. Helichrysum prostratum is also found in New Zealand, and it has white flower-heads. The flowers of Stilbocarpa polaris I have not seen in the living state; they are described by Kirk as “one-quarter of an inch in diameter, yellow, waxy, shining, with purple centres” (66, p. 215). The remaining plants have all small and inconspicuous flowers.
Thus, the difference so far as colour is concerned between a Pleurophyllum meadow and an allied formation in New Zealand proper is most marked. As to how such differences have come about is discussed under another head.