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New Zealand Plants and their Story

Chapter X. — The Story of Some Common Plants

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Chapter X.
The Story of Some Common Plants.

Relationships of the cabbage-tree—How gravity affects direction of growth— Fertilisation and seed-dispersal—Distribution of the cabbage-tree—Use of the tree in Maori times—The species of Phormium—The diverse stations of Phormium—Fertilisation by birds—The leaves of New Zealand flax—Use of flax by the Maoris—Garden varieties of Phormium—Diseases.

In the previous chapters a general account of the vegetation has been given rather than details as to special plants. In this and the chapter following a few of the commonest plants are dealt with, and something is told of their story, which, however, as yet is far from being a complete one.

The Cabbage-tree.

The cabbage-tree (Cordyline australis) is a most familiar feature in almost any New Zealand landscape, while it is also a favourite adornment of gardens, supplying there a special beauty of form generally lacking in the temperate vegetation:

But, although the plant m question is known so well, it may yet be news to some that it is no relative of the wholesome vegetable whose name it bears. It, on the contrary, -belongs to the same family as the Madonna lily, the hyacinth, and the tulip; or, if we must seek its relations below stairs, then to the onion, the garlic, and the shalot, whilst amongst its first cousins it boasts such useful members of society as aloes, squills, and sarsaparilla. Now, it is the structure of the flowers which places it in this most distinguished company, the outer floral, leaves being united at the base,* but divided above into six segments, the stamens also six in number; while the central portion of the flower, which finally contains the seeds, is three-chambered. At the same time, it differs from most of its kith and kin in its possession of a tall, erect trunk, being, in fact, a tree-or palm-lily, this latter page 138designation having been bestowed on account of its tropical-looking habit, for it is not really a palm.

Fig. 60.—Underground stem of Cabbage-tree, with numerous roots.[Photo, L. Cockayne.

Fig. 60.—Underground stem of Cabbage-tree, with numerous roots.
[Photo, L. Cockayne.

The trunk plays a most important part in the domestic economy of the tree, sending down deep into the ground what is popularly supposed to be a root. This, however, is nothing of the kind, but a deeply descending underground stem, which has the curious property for a stem of growing downwards while the aerial portion of the same trunk grows upwards, as should that of any well-regulated tree (fig. 60). Such growing upwards and downwards of stems and roots is regulated by that force we call gravity, which sets in motion the intricate and powerful "machinery" of the plant, just as a pressure of the hand lets loose that power which causes the mighty locomotive to move backwards or forwards, as the case may be. The descending stem penetrates the soil for a distance of several feet, giving off on either side long cord - like roots, which, passing outwards page 139and downwards, anchor the tree firmly, so keeping it erect. But the underground stem, besides functioning as a natural prop for the tree, plays a further and more important part, since there is stored up within its tissues the surplus food, manufactured within its green leaves from the carbon-dioxide of the air by the aid of sunlight. On this hoard the tree draws yearly, and the material is lent from which the huge mass of flowers is constructed. Should too much of the starchy food be used, or not enough have accumulated owing to an adverse season, there will be few or no flowers the succeeding year. A sufficient balance must-be kept at its bankers, as it were, or its life work will remain undone.

The dead leaves of the cabbage-tree are scrupulously removed every year by the tidy but too zealous gardener, and a long, naked stem results. Nature, however, loves not nakedness in any form— the bare rock she clothes with lichens, and the fallen giant of the forest with moss; so, too, she hides-the upper portion of our tree's trunk with a not inelegant covering of brown dead leaves. Nor is she mindful of beauty alone in so doing, for these leaves become saturated with moisture when the welcome rain falls, the trunk on its part putting forth many short but active roots, which must assist the leaves materially to the all-important water-supply hi dry weather. As for the leaves themselves, they are provided with a strong, fibrous skeleton, which enables them to defy the frequent gales; also, they are more or less erect, and thus escape the full force of the sun's rays—a decided benefit in the long, hot summer days; and, finally, their minute structure is such as to guard them against excessive loss of moisture in times of drought.

The cabbage-tree blooms during November and December; the flower-stems are much-branched, and crowded with small whitish flowers. These have a most powerful, though rather sickly, odour, which attracts crowds of insect visitors, who in return for the gift of sweet honey assist in bringing the dust-like pollen of the stamens to the stigma, and thus fertilising the egg, which in due course will then grow into a seed—that is, into a small body containing within it a tiny cabbage-tree. The seeds are black in colour, and angular, nine or less being enclosed in the succulent, three-chambered, milky-white berries. These latter are greedily eaten by birds, who thus assist in sowing the seeds far from the parent tree. Not only do the native birds engage in this work, but the introduced ones have learnt also to page 140
Fig. 61.—The Broad-leaved Cabbage-tree, or Ti (Cordyline indivisa). Mount Hauhnngatahi.Lands Department.] [Photo, L. Cockayne.

Fig. 61.—The Broad-leaved Cabbage-tree, or Ti (Cordyline indivisa). Mount Hauhnngatahi.
Lands Department.] [Photo, L. Cockayne.

page 141play their part, and so there is little fear but that the cabbage-tree will always remain with us as a truly wild plant; in fact, in some parts of New Zealand it is on the increase, as in the swampy ground of northern Auckland, where, when the close-ranked kahikatea forest is felled, stately files of this graceful tree rise up in its stead.

The genus Cordyline is somewhat widespread, its species being found wild in southern Asia, the Malay Archipelago, the Pacific islands, Australia, New Zealand, and South America. The special species we are considering, C. australis, is confined to New Zealand; but, though it is extremely abundant in the two main Islands, and its fruits are readily spread by birds, it is found in only one locality in Stewart Island, and does not occur at all in either the subantarctic islands or the Chatham Islands.

There are four other species of Cordyline in New Zealand, one of which, the toi (C. indivisa) (fig. 61), is a magnificent object, with its broad, arching leaves furnished with a conspicuous orange-coloured midrib. It is common at rather high levels in the North Island, but descends to sea-level in the South at the Otago Sounds. On the east of the South Island are a few plants on Banks Peninsula. Where the service road to the Main Trunk line has been made along the base of ice-capped Ruapehu, and the forest has been cleared, are splendid natural plantations of this beautiful tree, which grows in some places, indeed, by the thousand.

The common cabbage-tree is easy of cultivation. It will grow in almost any kind of soil, and may be readily raised from seed, this being the best method to secure a stock of plants. When a tree is cut down level with the ground it does not die, but will usually put forth new shoots from the underground stem. Even at an early age it is very ornamental, and young specimens, whose trunks are not yet developed, are eminently suitable for small gardens. There is a purplish-leaved variety, and also one with variegated foliage. Moreover, the cabbage-tree is a variable species, and many forms distinct for garden purposes may be met with in the wild state.

In a land where the natural vegetable products were not of much economic value, the most unlikely plants were pressed into the service of the aborigines, and any possessing the slightest beneficial property were made use of. The cabbage-tree, or, as the Maoris designated it, page 142the ti, tikauka, or tirahau, served several purposes. The underground stem, since it contained a large supply of starch, supplied a nutritious if not an especially palatable kind of food, and the leaves were plaited into flat or round ropes. In the north, however, C. pumilio was much more prized for food. Cordyline indivisa was still more esteemed for its fibre, which, according to Colenso, was woven into a durable mat called toii, which was dyed black.

In Europe the cabbage-tree is much prized for horticultural purposes, though it is hardy only in the warmer parts. In the Scilly Isles it is used for hedges, making wind-screens to the fields of daffodils, there grown so extensively for the London market. Strange to say, many New Zealand plants, the cabbage-tree amongst the number, grow luxuriantly in the Isle of Arran, Scotland, which are only half-hardy farther south: a fact which recalls Stewart Island, where in certain parts trees peculiar to northern Auckland are cultivated with success, but which cannot endure the climate of the Canterbury coast.

* The coloured leaves of the flower in the lily family are in two series, and in certain of the genera are not united below into a tube.

The New Zealand Flax.

Still more common than the tree just dealt with, and equally well known to all, is the New Zealand flax. This is another misnomer, as popular names usually are, since the species in question is no flax at all, but another member of the lily family, consequently a near relative of the cabbage-tree, the true native flax being a pretty white-flowered herb (Linum monogynum) common along the sea-coast. Although still extremely abundant, the flax has much diminished in numbers since the advent of the European, for the simple reason that it occupied the very ground most suitable for agriculture. Where the golden grain waves in the breeze, and where the lamb, unconscious of its doom, crops the lush grass, were formerly vast swamps, closely filled with the gigantic sword-like leaves of the plant, beneath whose friendly shelter countless red-legged pukeko sought their food, safe from their dreaded enemy the hawk.

The genus Phormium, to which the New Zealand flax belongs, is found only in Norfolk Island and New Zealand, and consists of but two species, P. tenax and P. Cookianum, this latter formerly known as P. Colensoi. These are readily distinguished by their "pods," those of the former species pointing upwards and not twisted, while the latter's droop downwards and are twisted. Further research may page 143perhaps show that these species are made up of a large number of varieties which produce themselves "true" from seed.

New Zealand flax grows in most diverse stations, and the structure of its leaves probably varies much according to environment. Faces of dry cliffs, clayey hillsides, swamps, and sandhills are some distinct spots where P. tenax flourishes. Nor is it fastidious as to climate. The warm valleys of northern Auckland, the wind-swept shores of south Westland, the bleak moorlands near Invercargill, the quaking bogs of the Chatham Islands, all afford it a suitable home. This Chatham Island form is distinct from the typical variety, its leaves being thinner, broader, and drooping, and its fibre comparatively weak, but very fine. There is also a small amount of flax on the Auckland and Campbell Islands; but it is not indigenous, having been planted there by the Maori sealers many years ago.

The flowers of the flax are not very showy, being of a Iurid red in P. tenax and yellow in P. Cookianum. The pollen is usually ripe before the stigma of the same flower is ready to receive it, a fact which points to cross-fertilisation as a possible cause of the great variation of the species. The abundance of honey contained in the flowers attracts the tui and other native birds, who assist in the work of fertilisation, playing the part performed in many plants by insects.

The leaves spring from a short but stout creeping stem, and this latter, spreading over the ground, helps to increase the spread of the plant. It grows readily from seed also; and from the seedlings, if raised in a sufficient quantity, new varieties might be expected.

The leaves are stout and thick, and stand erect, thus avoiding the direct rays of the sun—a contrivance against loss of water, as shown before. That a swamp plant should require protection against drought seems absurd, but this special drought-combating structure it is which permits the plant to inhabit rocks, dunes, and other excessively dry stations mentioned above. Nor does it seem unlikely that the flax has been driven into the swamps by its competitors, and lives there not from choice, but from necessity, though its drought-resisting structure is no longer an advantage, unless the water of the swamp be acid.*

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The harakeke, as the Maoris call the flax, was their most important plant, for on it their supply of clothing almost entirely depended. Dress mats of great variety were made from its fibre at an infinite expenditure of patience and labour. Some of these were dyed various colours, and were provided with elaborate borders. It also played its part in the Maori pharmacopoeia, being prepared in various ways for external application chiefly. From the dry flower-stalks, the korari, the Morioris of the Chathams built their fragile canoes.

Like the cabbage-tree, the flax is an admirable garden plant, and there are a number of very distinct varieties. Of these the principal are various variegated forms belonging to both species. Some, if not absolutely "true" to seed, certainly yield a large percentage of variegated plants; others, again, will put forth green leaves, and finally revert to the type, as did an especially fine specimen the author collected a number of years ago on the flanks of Mount Sherwood, in southern Marlborough. There is also a showy purple-leaved variety, especially striking when young, and a pleasing form with rather bronzy drooping leaves, marked with a dark line on the margin. Beyond the borders of New Zealand the flax is cultivated for ornament in all civilised lands.

The Maoris, too, cultivated the plant to some extent, and gave names to the different varieties. Hector's work, published in 1872, enumerates no fewer than fifty-six. But doubtless many of these are identical, while it is probable that the same name was used by different tribes for distinct varieties; consequently, the Maori names are of little moment. Yet it must be noted that some of the Maori varieties contain a much better class of fibre than that of the average swamp plant.

Botanically, Phormium tenax is a most variable plant. The colour of the leaf-margin and midrib, the length of leaf-butt, its interior colour and gum-content, the stiffness of leaf, the breadth of leaf, the form and colour of flower, and the shape, size, and direction of growth of the pod— all these and other characters differ in different individuals. Indeed, it needs a close examination of any specimen and a long experience with flax - variation before one is able to select different varieties from the heterogeneous mass of a phormium swamp.

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Phormium tenax, although an indigenous plant, is not immune from "pests" of various kinds, some of which are vegetable and some animal. Circular black spots formed by a microscopic fungus (Cladios-porium) cause not only the premature death of the leaf, but also render the fibre discoloured for milling purposes. Leaf-spot is a worse disease still, red discolorations being formed on the surface of the blade. Perhaps the worst enemy of the plant, and certainly of the flax-miller, is an indigenous slug which eats out patches on the under-surface of the leaf. Strange to say, according to the researches of T. W. Kirk and A. H. Cockayne, "these gouged-out portions of the leaves are frequently attacked by a fungus (Rhizopus nigricans), but this fungus never seems to attack healthy plants." The leaf-margin is the point of attack of various caterpillars, who cause jagged wounds.

* See remarks on physiological dryness in Chapters V and VII.