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The Vegetation of New Zealand

Chapter II. — The leading Physiognomic Plants and their Life-forms

Chapter II.
The leading Physiognomic Plants and their Life-forms.

Dune plants.

Desmoschoenus spiralis (A. Rich.) Hook. f. (Cyperac.) pingao, is a stout, far-spreading sand-binding sedge. The rhizome, many metres long, is about 1.7 cm. diam., somewhat woody, much-branching and covered with old leaf-sheaths. At first, it creeps close to the surface, but is soon buried and forms eventually a tangle of rope-like stems in the sand. The leaves are in bunches tightly bound together at their bases by the sheaths so that a bulbous mass about 2.5 cm. diam. is formed, but they gradually open out, curving somewhat inwards. The sheath is about 10 cm. long by 5 cm. broad at the base, moderately thick in the centre, translucent and membranous at the margin, and sticky everywhere with a resinous exudation which helps to bind the sheaths together. The blade, 60 cm. long by 7 mm. broad, tapers gradually to a long trigonous point; it is thick, coriaceous, stiff but flexible, concave on the upper and convex on the under surface to that the leaves fit one into the other. The colour is a rather dark glossy green near the base and on the under surface, but the upper surface, especially above, is frequently orange-coloured or reddish, though the leaves, as a whole, viewed from a distance appear yellow. The branches are given off so closely that the separate leaf-bunches touch making semi-tussocks or continuous lines.

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Spinifex hirsutus Labill. (Gramin.) is a powerful sand-binding grass with an extremely long, much-branched, smooth, hard woody flexible creeping-stem, which puts forth numerous, wiry roots which descend deeply into the sand. The leaf-blade is usually about 47 cm. long by 10 mm. broad and tapers to a fine point; it is thick, coriaceous and flexible and both surfaces are covered thickly with pale adpressed hairs; its sheath is 11.5 cm. long, pale, thick and fleshy. The flowers are dioecious; the male spikes numerous, about 8 cm. long and forming a terminal umbel with sometimes 2 to 3 spikes making a cluster below. The female inflorescence is a large globose head, sometimes 30 cm. diam., composed of 1–2-flowered spikelets each at the base of a long, sharp-pointed, radially spreading spine some 12.5 cm. long.

Carex pumila Thunb. (Cyperac.) is a small grass-like sedge having a long, slender rhizome some 3 mm. diam. which gives off, at intervals, bunches of 4 to 6 fully developed leaves. The leaf-blade is thick, coriaceous, flexible, 30 cm. long more or less, glaucous-green and tapers gradually to a fine point; its upper surface is deeply concave through the curving margins. In position, the leaf is erect towards the base, but above it curves so that the apex almost touches the ground. The roots are long and slender. The culms are short, stout and about 15 cm. high. The utricle is large, thick, turgid and about 7 mm. long.

Coprosma acerosa A. Cunn. (Rubiac.) is a wiry shrub of the divaricating-form, but more depressed than usual for that class, which makes flattened, orange or yellow, open cushions, or thick mats, of flexible interlacing twigs and has a prostrate, rope-like, main stem about 1.8 cm. diam. which is either buried in the sand or hidden by the shoots. The leaves are small, coriaceous, pale-or yellowish-green, linear, about 7 mm. long, and situated in opposite pairs upon much-reduced branchlets. The roots are extremely long, but short adventitious ones are frequent on the peripheral shoots. The drupe is globose, fleshy, 7 mm. long more or less, translucent and white stained with pale blue.

Cassinia leptophylla (Forst. f.) R. Br., tauhinu; C. retorta A. Cunn.; and C. fulvida Hook, f., (Compos.) are erect, busny, ericoid shrubs, ranging from 1 m. to 2 m. high, and differing only in the colour of their tomentum and some slight distinctions in leaves and flowers. The main stems are few, naked, not much branched below, but above branch abundantly into slender leafy twigs which finally give off, at a narrow angle, flexible, straight branchlets covered with tomentum, either white (C. retorta), greyish (C. leptophylla) or yellow (C. fulvida). The ultimate shoots form close masses. The leaves are linear-obovate (C. retorta), or linear to linear-spathulate, about 3 to 4 mm. long, moderately thick and coriaceous, abundantly tomentose beneath but shining-green above. C. fulvida has glutinous branches and its leaf-and stem-tomentum give an almost golden colour to the shrub.

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The flower-heads are numerous and in terminal corymbs. The inner involucral bracts have white, radiating tips and so render the inflorescence conspicuous.

All the species, including the non-coastal, when they grow in close proximity gave rise to polymorphic hybrid swarms.

Salt-swamp plants.

Leptocarpus simplex (Murr.) A. Rich. (Restionac), oioi, jointed-rush, forms dense tussocks of erect, slender, stiff, wiry but flexible rush-like stems which vary in harmony with the intensity of the illumination from dull-green to bright red-orange. There is a rather stout rhizome, which, at times, growing erect and branching may form a trunk 20 cm. high. The leaves are represented by short, blackish, sheathing scales which clasping the terete stem at distances of 2.5 to 10 cm. give it a characteristic appearance. The roots are wiry and of medium length. The flowers are dioecious; the male inflorescence is paniculate with numerous reddish-brown spikelets, while the female is compacted into rounded glomerules alternating along the stem.

Juncus maritimus Lam. var. australiensis Buchen. (Juncac.) is of the ordinary rush-form and makes dense tussocks about 90 cm. high and 50 cm. diam. at the base. The dark-green, glossy terete stems and leaves taper gradually to a pungent but frequently dead brown point.

Plagianthus divaricatus J. R. Forst, (Malvac.) is a dark-coloured almost deciduous shrub of the divaricating life-form. There is a stout main stem some 5.7 cm. diam. which gives off several branches which passing upwards, and outwards, finally branch abundantly into short, wiry twigs given off at a wide angle and closely interlacing, the whole forming a dense, compact, elastic, rounded mass, a flat mat or an open cushion. According to the degree of exposure to wind, the periphery may be wiry and close, or twiggy and open. The naked interior stems are 3 cm. thick or more, twisted, curved and liane-like in appearance. The leaves on much-reduced branchlets, are very small, linear to linear-obovate, 7 mm. long and slightly coriaceous. The flowers are very small, pale yellow or whitish edged with purple, honey-scented and produced from September to October.

If, when growing on the banks of a tidal river, Plagianthus divaricatus meets P. betulinus, a swarm of hybrids between thems may occur. T. Kirk (1899: 70–71) based his species P. cymosus on one such hybrid collected in a Dunedin garden. The swarm is at its fullest development in the lower Pelorus Valley (SN.).

Avicennia officinalis L. (Verbenac.), manawa, mangrove, is a shrub or small tree varying in height from 60 cm. to 9 m., or even more,. As a tree, it has a stout, but usually short, main trunk from which a few short primary branches pass off, spreading outwards and branching some 4 or 5 times so as to form a round-headed fairly dense crown. The bark is rough, grey and much furrowed. The ultimate and subultimate twigs are brittle, slender, page 66much curved and marked with old leaf-scars. The leaves are ovate to ovate-lanceolate. 5 to 10 cm. long, thick, coriaceous, dark-green, rather glossy and with yellow midribs and veins and hoary pubescent beneath and frequently placed more or less vertically. The roots extend for a great distance laterally and this is emphasized by the hundreds of erect branches, (pneumatophores), which project out of the muddy substratum (Fig. 3). These erect roots are from 20 to 30 cm. long on an average; they are straight and taper from the base upwards to a blunt apex.

The inflorescence consists of small heads of 5 to 8 flowers each about 8 mm. diam. The fruit, which is ready to fall by the beginning of January, consists of a capsule some 4.2 cm. long by 2.8 cm. broad and 1 cm. thick; the pericarp is brown and leathery but thin enough for the penetration of sufficient light for the formation of chlorophyll. The embryo, which has no resting-period, emerges early from the seed-coat, so that by the time the fruit is ripe, it completely fills the cavity. At this stage, the embryo consists of the two thick, fleshy cotyledons folded longitudinally, the outer, which is darkgreen on its upper surface, tightly enclosing the inner, and the hypocotyl, which is about 10 mm. long, slightly projecting, while the much shorter epicotyl, which has two pale rudimentary leaves, is pressed close beneath the folded cotyledons. Already the hypocotyl possesses root-rudiments in the shape of small knobs surrounding the swollen apex, while above there is a ring of brownish hairs which project upwards. After falling from the tree the embryo, continuing to increase in size, splits the pericarp along its suture, and first one half and then the other being shed, the green embryo, its cotyledons still tightly folded and the blunt apex of the hypocotyl projecting, lies on its side in the mud, and may be washed hither and thither by the tide. As time goes on, the cotyledons open out by slow degrees; the hypocotyl lengthens and when it is about 2 cm. long and the outer cotyledon is quite raised from the inner the roots are obliquely penetrating the substratum and firmly anchoring the plantlet. Growth now proceeds rapidly, especially that of the roots, but it is a considerable time before the cotyledons become fully flattened out, in fact the plant depends upon their reserve-material and chlorophyll for a considerable period. Thus a young plant with its hypocotyl 4.5 cm. long, its epicotyl 3 cm. long and the first two foliage-leaves 2.5 by 1.5 cm. has the laminae of the cotyledons still considerably folded. Pneumatophores appear quite early, so that a root 50 cm. long arising from a young plant 70 cm. high, may have two of them each about 14 cm. long.


Corynocarpus laevigata J. R. Forst. (Corynocarpac.), karaka, (Maori), kopi (Moriori), is an exceedingly handsome small tree 6 m. to 12 m. high with a regular trunk 30 cm. to 60 cm. diam. covered with rather thick bark rough with lenticels, and a dense, rounded, glossy-green head which during March and early April — according to latitude — is covered with page 67showy, fleshy, orange-coloured drupes 2.5 cm. long. The leaves are ellipticoblong or oblong-obovate, 7.5 cm. to 20 cm. long dark-green, smooth and shining.

Metrosideros tomentosa A. Rich. (Myrtac), pohutukawa, christmas-tree, occurs in various epharmonic forms, which range from a massive tree, 21 m. high with a trunk 60 cm. to 90 cm. diam., to a small, stiff-stemmed shrub 30 cm. to 60 cm. high, but usually taller. As a tree, it is frequently of an irregular form, especially when its trunk projects more or less horizontally from some coastal cliff. At other times the trunk may be short whith numerous erect trunk-like branches, issuing apparently from the ground, and in some cases growing into one another. The bark is brown, much-furrowed and wrinkled. Many adventitious roots are given off even from quite high up (Fig. 4.), and may form bunches, but those lower down often assume great dimensions and assist materially in anchoring the heavy trunk to a rock-face. The branches are massive and wide-spread and after branching several times finally give off numerous, stout, straight branchlets which bear the decussately arranged leaves and are white with a close covering of tomentum. Boughs, branchlets and leaves form a close head on the tree. The leaves are from lanceolate to broadly oblong, 2.5 to 10 cm. long, darkish-green, very thick, coriaceous and clothed beneath with white tomentum, but this is absent in seedling and juvenile plants. The flowers are arranged in broad, terminal, many-flowered cymes on stout tomentose peduncles and pedicels. The calyx is also tomentose, and functions in protecting the flower-bud. The flowers are dark crimson, so that a tree in full bloom is a magnificent spectacle.

Hybrids occur between Metrosideros tomentosa and M. rohusta and 3 of such are united by Carse under the name X Metrosideros sub-tomentosa, but such cannot be types of the whole swarm.

Myoporun laetum Forst. f. (Myoporac.) ngaio, is a small tree, averaging some 6 m. in height, with a trunk 30 cm. or more diam. covered with deeply furrowed bark 5 mm. or so thick. The crown consists of straggling, spreading branches which finally give off numerous, flexible, stout, leafy twigs, viscid at their tips. The individual branch-systems frequently do not touch so that a good deal of light can pass to the ground beneath. The leaves are lanceolate to obovate, 2.6 to 10 cm. long, acute or acuminate, glabrous, soft, flaccid, moderately thin, darkish-green but looking paler than they really are owing to the numerous oil-glands dotted over the surface. The flowers are in clusters of 2 to 6 in the leaf-axils; each is about 13 mm. diam., the petals are white dotted with purple. The drupes are purple, oblong, 8 mm. long and succulent.

The coastal Ferns.

The following coastal ferns require notice: Asplenium obtusatum Forst. f., Blechnum durum (Moore) C. Chr. and B. Banksii (Hook, f.) Mett. All grow under identical conditions and are ecologically page 68similar. They thrive best in an equable moist climate with low summer temperature and cloudy skies, and rapidly form raw humus out of their dead parts.

Asplenium obtusatum varies epharmonically in size but is generally a rather large fern. There is a thick rhizome sometimes 30 cm. long and 3.5 cm. diam. The leaves are erect, pinnate with 6 to 20 pairs of close-set sometimes overlapping pinnae, dark-green, linear-oblong, 6 to 30 cm. long, and the stalk is from 5 to 15 cm. greenish to almost black, very stout and channelled above. Large examples have leaves 67 cm. long by 19 cm. broad.

Blechnum durum has a stout rhizome and, in large examples, a distinct trunk 12 cm. or more high and 5 cm. diam. clothed with the old leaf-bases. The leaves which have a short stalk 2.5 to 5 cm. long are arranged in erect. semi-erect or almost flat but recurved rosettes at the summit of the trunk or rhizome. They are lanceolate, dark-green, shining and frequently about 43 cm. long by 4 cm. wide, though much smaller and larger dimensions are common. The pinnae are numerous and close-set, the upper frequently overlapping; at first lanceolate they gradually decrease in length until the lower-most are reduced to rounded auricles. The sporophylls are shorter and narrower than the foliage-leaves.

B, Banksii, an altogether smaller fern than the two preceding, is closely related to B. durum, but the leaves are flattened to the substratum. It appears to be confined to rocks or their immediate neighbourhood, whereas A. obtusatum and B. durum are common plants of forest near the sea and coastal moor.