Art. XXX.—Some Observations on the Coastal Vegetation of the South. Island of New Zealand.—Part I: General Remarks on the Coastal Plant Covering.

By L. Cockayne, Ph.D.

1. Introduction.

In this series of papers no attempt will be made to give a detailed description of the whole coastal vegetation of the South Island. This introductory paper is purposely quite general, and intended chiefly to pave the way for future work, and to save repetition when dealing with the formations themselves. As for these latter, only those will be described which I have had some special opportunity of examining during the last few years. Each account will treat of some special part of the coast, and be complete in itself, therefore no classification of the formations will be attempted, nor any such presentation of them in a connected sequence as would be necessary were the coastal vegetation of the South Island as a whole the theme. The treatment of the formations, too, will be far from exhaustive. Such can only be expected from local botanists. Some attempt, however, will be made to give a word-picture of each formation, and details will he furnished regarding the conditions under which such exists, while something will be said as to the life-forms of the most important constituents. As in my former phytogeographical papers, the term “formation” is adhered to on the score of priority,^* while that of “association” is restricted to those smaller combinations or groups of plants which are frequently clearly defined within a formation.^†

At the conclusion of this paper are included, in the Bibliography, the names of the more important papers referring to my subject. It must, however, be pointed out that these usually contain but little matter of ecological interest, and that for the most part they are lists of plants. In fact, so little has, up to the present time, been published regarding the coastal vegetation of the South Island that I do not consider it necessary to give a summary of our knowledge on the subject.

Properly speaking, the South Island of New Zealand does not form a distinct phytogeographical province. Strange as it may seem, Cook Strait forms no line of demarcation between the North Island and the South Island floras—so far, at any rate, as the lowland region is concerned. It is not until latitude 42°^‡ south is reached that the South Island vegetation

properly commences; but it must be pointed out that this limit is at best but a very artificial one. Notwithstanding the above, it is a convenient and quite legitimate plan to discuss the vegetation of either Island as a whole, and the method of treatment here adopted can, with the above explanation, lead to no misconception.

Regarding the term “coastal vegetation,” it is not generally feasible to set any hard-and-fast limit as to its boundaries. Generally speaking, it is confined to quite a narrow zone following the coast-line, and determined, amongst other things, by the salt in the soil, the average distance sea-spray may blow inland, and the configuration, of the land. In some places there are distinct traces of ancient shores, and such may contain in large part maritime plants, but unless these are in fairly close proximity to the sea they will not be specially dealt with.

As some of the notes, &c., made use of in the preparation of this paper were taken during several voyages in the Government steamer “Hinemoa,” I thank most sincerely the Hon. W. Hall-Jones, M.H.R. (at that time Minister of Marine), for the opportunities thus afforded of visiting some little-known places on the coast and many of the adjacent small islands. To Captain J. Bollons, who assisted, me in every way possible to carry on my work, my most hearty thanks are due. I must also express my gratitude to Messrs. F. G. Gibbs, M.A., D. Petrie, M.A., H. J. Matthews, J. Crosby-Smith, and T. F. Cheeseman, F.L.S., who have furnished me with much valuable information, and in other ways materially assisted this work.

2. Physiography and Climate.

The extensive coast-line of the South Island, facing the actual ocean for some 4,845 km., and extending in many places far inland, affords, as may well be supposed, a very considerable diversity of stations for plant-life, with the consequence that a by no means uniform plant covering clothes the shore and its environs. This absence of uniformity, far greater than might have been expected from differences of latitude, is in large part due to the fact that, thanks to the position of the Southern Alps, a quite different climate occurs, generally speaking, in the east than in the west, south, and many parts of the north. In fact, to mention two extremes, the west has an average rainfall of more than 253 cm., the extreme south-west corner having, in-

brooks and springs. Streams, too, sometimes flow over the shore. In both these cases special conditions occur for plantlife, but such, it may be pointed out, are not coastal unless salt be present in excess.

3. Ecological Factors.

The special factors with regard to coastal vegetation are superabundance of salt in the soil, and high or frequent and prolonged winds. Together with these comes a more equable climate than further inland, so far as extremes of temperature are concerned, but at the same time there is often strong insolation and bright illumination. The biotic factor, apart from introduced animals and those concerned in fertilisation, is of little moment, with the exception of the part played by the small land-crabs in the salt meadows, whose innumerable holes must assist materially in aerating the soil, and to some measure, also, in draining the ground.

As for the salt in the soil, this comes either through the flooding of the ground more or less frequently, or through sea-spray blowing inland. The effect of the former is strongly marked, and on it the most typical halophytio formations depend—e.g., salt meadows, salt marshes, and brackish-water vegetation. As for the effect of sea-spray, it has probably been very much overestimated. Quite recently T. H. Kearney (27) has shown this to be the case for certain parts of the east coast of North America, and he comes to the conclusion that dune plants, and even those of the strand, for the most part do not owe their adaptations against transpiration to excess of salt in the soil, but to other conditions, and that they are rather ordinary xerophytes than halophytes.

The above explanation seems to meet New Zealand conditions. Thus, the large shrubby nettle, Urtica ferox, is a common maritime plant, growing in some instances on the upper strand not far from high-water mark. But, as is well known, that genus is one which is distinctly averse to salt in the substratum (Warming, 44; p. 304). Macropiper excelsum, another frequent coastal plant, belongs also to the same category. Mesembrianthemum australe, an extremely succulent plant, usually grows on the face of cliffs, where salt could not penetrate to any extent. The “coastal scrub” at the base of the Bluff Hill would most certainly be non-existent were there excess of salt in the soil, and yet some of its members overhang rocks covered with seaweeds. In short, the effect of spray seems to be largely dependent upon the position of a formation with regard to the prevailing wind, and upon the frequency and force of this latter. And this brings me to the point that, in New Zealand at any

depended rather on edaphic than climatic conditions—i.e., on subsoil water rather than number of rainy days.

The above rain-forests are not, strictly speaking, “coastal,” but are merely the ordinary lowland forests of the particular locality. But their seaward margin is frequently distinctly-modified by coastal conditions. Thus, there may be a dense growth of shrubs or low trees, as originally pointed out by Hector (21), forming a definite plant-association or maybe formation, which at times exhibits a zonal arrangement of its members, defined by their wind- or spray-resisting powers, the trees or shrubs being gradually more xerophytic from within outwards. In other places Phormium tenax may form a natural wind-break between the forest and the actual shore, reaching so close to the water that seaweed and pieces of driftwood maybe stranded at its base.

Certain edaphic formations are not affected by the rainfall. Thus the dunes at Martin's Bay, in the very centre of the wet region, maintain clearly their desert character, while at the head of the western sounds far inland in the heart of vast forests are muddy flats covered with the usual halophytes. With rock formations, on the other hand, it is quite the contrary. These vary much in their plant covering according to the rainfall. On the dry east coast, masses of the succulent Mesembrianthemum australe depend from rock-crevices and alone hide in a few places the bareness of the surface. But in the west great walls of rock are covered with arborescent plants, the constant wet being most favourable for peat-production, which, lodging on ledges, and in hollows, forms a thin soil, which the plants can use, thanks to the far lateral spread of their roots. Between such fertile cliffs and those of the east there are many transitions in, harmony with the water conditions of the station.

4. Dunes, Salt Marshes, and Salt Meadows.

The absence of uniformity in the coastal formations, as mentioned previously, is not without some striking exceptions. Such are found in the case of those before mentioned formations-which depend on some special edaphic rather than climatic influence. Of these, the most common are dune, salt-marsh, and salt-meadow formations. Not only are dunes, salt meadows, and salt marshes remarkably uniform throughout the South Island, but through nearly the whole of the New Zealand biological region—a sandhill in the north of Auckland, for instance, not differing much from one of the extreme south of the South Island, Stewart Island, or even of Chatham Island (12; p. 259 et seq.). To find a dune floristically and even ecologically distinct one must visit the Auckland Islands, whose sandhills

contain none of the characteristic New Zealand psammaphytes (13; p. 237). But there are a number of differences in New Zealand dunes, and these are sufficiently marked to enable a botanist conversant with the coast to tell within certain limits to what part of New Zealand a particular sandhill would belong. One example will suffice here, and, as it is an interesting case of representative species, it is worth emphasizing. The genus Cassinia is represented in New Zealand by six species, one of which—C. albida, Cockayne—would be considered by many as a variety only, and another, C. amœna, is confined to the North Cape. As for the remaining four, all are common at sea-level, while two of them ascend into the subalpine region. As for their life-forms, they are very similar, being of the ericoid, sclerophyllous type with tomentose leaves. Commencing at the subantarctic islands, C. vauvilliersii occurs near the coast to the south of the South Island, where it is succeeded by C. fulvida, this in its turn giving place to C. leptophylla in the central province, and this to C. retorta in the northern province. Everywhere Scirpus frondosus is the leading sand-binding plant, but in the central and northern provinces this is reinforced by Spinifex hirsutus. But no more need be said here as to the above edaphic formations, as they will receive detailed treatment in the special part of this series.

5. Physiognomy of Coastal Vegetation.

Formerly the physiognomy of vegetation was merely a geographical concern pure and simple, but this is no longer the case, since it is recognised that the life-form of a plant is a physiological matter depending on the relationship of form to outer factors and to inner causes. This being so, the general appearance of the landscape as determined by the presence of certain dominant species becomes an affair of high biological interest. Now, the scenery may be affected in two ways: either some particular plants or life-forms may be especially striking, or it may be a group or even the character of a whole formation that may specially catch the eye. Thus, taking New Zealand as a whole, the scenery is distinctly affected by the abundance of Cordyline australis and Phormium tenax, while that life-form the “tussock” is perhaps the most striking characteristic of large areas. On the other hand, where forests dominate the landscape their individual members exert little influence, it being their evergreen character and close growth which stamps their physiognomy.

Coming now to the subject of this section, Cordyline australis, Phormium tenax, P. cookianum, and tussock - grasses play frequently quite a prominent part in the physiognomy of the

slopes in the east are covered with, brown tussocks of Poa cœspitosa, from amongst which rise up dark-coloured semi-pyramidal masses of the liane Muehlenbeckia complexa, which has assumed a shrubby habit, and stiff, erect, dull-green bushes, quite leafless, of a species of Carmichœlia.

Many other physiognomic peculiarities could be cited, but it would lead to a general account of formations, here obviously out of place. Other characters which affect the landscape depend upon the blooming of various plants, and this is dealt with to some extent in another section.

6. The Small Coastal Islands; Endemism.

Not the least interesting portions of the coast, if they may be so included, are the islands situated at no great distance from the mainland with which they have been connected at some earlier period. Of such islands some have been inhabited for a considerable time, while a few are still in their virgin state (14). In the former case the effect of man and herbivorous mammals on a primeval vegetation is fairly easy to estimate, since their area is small enough for close observation. Dog Island and Centre Island, which are to be treated of, are of this class, while the Open Bay Islands and the yet unexplored Solanders belong to the other category. The limited size of these small coastal islands, too, permits detailed observations, to be taken as to the distribution of formations, the effect of introduced plants, the change of edaphic conditions on the vegetation, and the like. Finally, it is in such spots that relics, either of former vegetation not existing elsewhere or of incipient species might be expected.^* As for the latter, a variety of Brachycome thomsoni named minima is reported by Kirk for Dog Island (34; p. 260), and I mentioned a form of Veronica elliptica as peculiar to the Open Bay Islands (14a; p. 371). On East Cape Island, in February, 1905, I collected a very robust and fleshy plantain, which is either a new species^† or Colenso's P. picta. Other examples are afforded by the more distant islands—e.g., Veronica gigantea of Chatham Island, closely related to the common V. salicifolia, and Acœna sanguisorbœ var antarctica of the Southern Islands.

But it is as a haven of refuge that islands figure more conspi-

spread,^* and it is hard to believe that the Australian Styphelia richei did not reach the above group by way of New Zealand originally.

7. Southern and Northern Limits of Coastal Plants.

The coastal formations consist, as is shown further on, of two classes of plants—viz., the coastal plants proper, and those which are common inland. Now, although the strictly coastal plants are usually of wide distribution, not only in the South Island, but through much of the New Zealand biological region, some are confined to a small area, and others again only reach a certain distance to the north or the south, as the case may be. Considering first this latter category, the question is at once opened up as to the reason why certain plants have a definite northern and southern limit. This inquiry is much easier to propound than to answer in the present state of knowledge. At first sight the matter under consideration might seem merely to be a question of climate—that when, say, a northern plant t of a frostless climate reached a point where frost occurred, it could advance no farther; or such a plant, again, might require for its well-being a certain average maximum of heat. But an examination of the facts shows that there is something much more far-reaching in the matter than the above; but this can be best understood by citing some specific examples. Take, first of all, the case of the kauri (Agathis australis), which, although not a coastal tree, may fairly be used as an example, since the matter under, consideration concerns the whole New Zealand flora, while the kauri, moreover, is one amongst a number of plants which are confined to the north, roughly speaking, of the 38th parallel of latitude. Now, south of this line for a considerable distance, especially on the west of the North Island, there are no climatic conditions which should inhibit the growth of this tree in many places. Moreover, at Wellington, more than 3 degrees to the south of the kauri limit, this tree grows famously in cultivation, producing cones regularly. Even at Christchurch, in the South Island, in the Domain, where —9° C. has been frequently recorded, the kauri grows well and has recently fruited. Also, a young plant has withstood the cold of this winter in the garden of the biological laboratory, Canterbury College, in a position where it could get no sun, and where a plant of Veronica elliptica collected by me in Campbell

this line many of the northern species and genera ate wanting, but a large proportion extend south, some just crossing Cook Strait, others finding their southern limit at Banks Peninsula, or at other definite points east and west, while others, again, extend right to Stewart Island and even to the Southern Islands. In the same way the subantarctic element, including in this some of the endemic genera—e.g., Celmisia, Olearia, Aciphylla—has pushed northwards, leaving here and there outposts or settlements cut off from the main body, such as the Crassula moschata at Island Bay, Wellington, before mentioned, but especially the patches of Nothofagus in northern Auckland. Generally speaking, in this struggle the subtropical element is the conqueror, the subantarctic plants being driven into the more unfavourable stations, such as lowland bogs, the subalpine region where pure Nothofagus forests nourish, or alpine heights.

As to how finally the various combinations of plants have come about which make the formations and associations, it seems in the present state of knowledge vain to inquire. The action of minor climatic changes is but little known. Our ignorance is great regarding the mutual reactions of plants on one another when brought into contact, reactions which must have much to do in determining what plants shall finally occupy a station. In this matter experiment is imperative, and a fruitful field is open in New Zealand, where, with the introduction of so many exotic plants and animals, unpremeditated experiments are even now in progress everywhere.

Finally, to sum up the matter, all that can be said about the distribution of the New Zealand coastal plants is that it is the resultant of a large number of causes. The historical factor and evolution determine the species, climate and soil sort them out into groups, and the struggle for existence, which is governed by the life-forms and constitutions of the competitors, finally fixes the formation—that is, so far as a formation may be termed a fixed entity.

8. Local and Limited Distribution.

Coming now to those plants mentioned above as being confined to a small area, the following citations must suffice, but these include some of the most striking amongst New Zealand plants: Helichrysum purdici occurs, so far as is known, only in one or two stations on the north shore of the Otago Harbour, and there are only a few plants in each locality. I found by cultivation that this plant would not endure much frost. Olearia insignis, so far as its coastal distribution is concerned, is limited to cliffs on the Marlborough. coast,^* and it is sometimes accom-

panied by the beautiful Veronica hulkeana. Celmisia lindsayi occurs only on rocky faces and stony débris in the neighbourhood of the Nuggets and Catlin's River, south-east Otago.^* This is a remarkably easy species to cultivate. The thickets of Olearia operina are found only at the West Coast Sounds, and the closely allied O. angustifolia, so far as its South Island distribution is concerned, has been recorded from only one locality, the base of the Bluff Hill, Foveaux Strait, although it is an abundant plant on some parts of the coast of Stewart Island and the neighbouring small islets. Capsella procumbens, one of Petrie's numerous discoveries, has been recorded only from Oamaru. Lepidium banksii occurs only on the southern shores of Cook Strait. Stilbocarpa lyallii, a common plant of Stewart Island and of some of the islands adjacent, is found, according to Kirk, only in the South Island in the vicinity of Preservation Inlet.

9. Primitive and Modified Formations.

The coastal plant formations of settled districts are usually in a much more primitive condition than are those of the adjacent lowlands. The nature of the soil, and its possession in some instances of more salt than is beneficial for the majority of plants, has had the effect of keeping away the rank and file of the invading host of foreign plants which now form such a marked feature in many districts in New Zealand. Certain parts of the coast, especially in the west, are far removed from the inroads of domestic animals, and there the plant covering is truly primeval. On the other hand, certain formations, which at first sight, appear primitive, on a closer examination prove to have been modified considerably by fires, drainage, grazing animals, and introduced plants. For instance, the majority of dunes at the present time are certainly much more unstable than they were originally, their great protector, Scirpus frondosus, being eaten by rabbits and other animals.^† Also, these dunes, inhospitable as they appear, are not seldom thickly occupied by introduced plants, which have quite overcome the original plant inhabitants. A very striking case is that of Lupinus arboreus, introduced in the first instance as a sand-binding plant, but which now forms dense thickets in all parts of many dunes except the most unstable. Also, Ulex europœus and Sarothamnus scoparius, planted originally as hedge plants, occupy wide areas and frequently struggle with each other and with the tree-lupin for the supremacy. In some places the forest which came to near high-water mark has been cut

down, and a second growth, easily mistaken for a primitive one, now occupies the ground. An actual sea-beach, may be occupied exclusively, or almost so, by introduced plants. Thus the steep, unstable gravel beach at Kaikoura abounds with Sherardia arvensis and Scandix pecten-veneris, the only indigenous plant-present being Rumex obtusifolius.^* The effect of drainage may be well observed where such operation has been carried on in a salt meadow, the native plants decreasing as the ground gets drier, and finally introduced grasses being dominant. Even slightly brackish water is not free from the foreign element, the customary dense red mat of Azolla having to give place to Glyceria fluitans, or to the watercress, Nasturtium officinale.

10. Mountain Plants on the Coast.

There is at times a close ecological resemblance between some coastal plant formations and those of higher altitudes. This is probably owing to the fact that somewhat similar climatic and edaphic conditions are provided. Alpine plants must in many instances have been driven into the mountains by a more vigorous lowland vegetation, such as lowland mixed forest or tussock meadow, and where these formations cannot exist—e.g., owing to sea-breezes, halophytic conditions, or a too scanty supply of soil, such as rocky places or a gravel beach provide—then subalpine or alpine plants, or those ecologically related to such, may find a haven of refuge. The Olearia insignis formation alluded to above is an excellent example, since it not only occurs on cliffs facing the ocean and lapped by the waves, but, with few members added or changed, it ascends high into the mountains. Claytonia australasica, a plant of stony, subalpine river-beds, shallow running water, and alpine shingle - slips, descends to sea-level on sandhills near Dunedin (37; p. 544), and also on the shores of Foveaux Strait. Helichrysum selago, a shrub of subalpine and alpine rock-faces, occurs on ancient sea-cliffs near Cape Saunders, Otago Peninsula. In the West Coast Sounds, Cordyline indivisa, a plant of subalpine of montane forests, is not infrequent on cliffs quite near the water's edge. Coastal scrubs, as I have pointed out elsewhere, are frequently closely related to subalpine scrub, both ecologically and floristically. Finally, to quote an easily observed North Island example, certain shady cliffs near Island Bay, Cook Strait, have a fairly rich vegetation of Phiormium cookianum, Aciphylla squarrosa var., Senecio lagopus, and a broad-leaved

form of Craspedia fimbriata, while on the stony beach are large, circular, silvery patches of Raoulia australis.^*

Many more examples of mountain plants growing naturally at abnormally low altitudes could be given, but the subject is of too much importance for a brief treatment such as could be afforded here.

11. Occurrence of Coastal Plants Inland.

So long ago as 1871, Mr. T. Kirk (29) pointed out how certain coastal plants occurred far from the reach of tidal waters in the, Waikato district. Among these species were such well-known coastal plants as Selliera radicans, Ruppia maritima, Scirpus maritimus, and Leptocarpus simplex. To explain this distribution Kirk called in Hochstetter's conception of an ancient shallow arm of the sea in the middle Waikato basin. Since that time many more facts as to occurrence inland of coastal plants have been recorded. Thus several occur on the shores of the central North Island lakes, of which perhaps the most interesting is the beautiful tree Metrosideros tomentosa, which occupies similar positions on the cliffs of Lake Taupo, Lake Rotoiti, &c., to what it does on the coast of the northern floristic province. Near hot springs at Ohinemutu and elsewhere grow Leptocarpus simplex and Triglochin striatum filiforme.

The South Island also supplies some interesting examples. On the Maniototo Plain or its neighbourhood Petrie recorded Chenopodium triandrum, C. glaucum ambiguum, Atriplex buchanani, Senecio lautus, and Ranunculus acaulis. From near Lake Wanaka he collected Selliera radicans (37). Linum monogynum occurs on the upper Canterbury Plain and reaches to the base of the Southern Alps, and to similar altitudes in south Nelson. Angelica geniculata, which Kirk did not believe to extend inland, was noted by me at a slight elevation on the Rock and Pillar Range, Otago, and also at the Lower Waimakariri Gorge, where it is accompanied by other coastal plants.

How far all the above cases denote a former shrinkage of the land and extension of the coast-line inland is not for a botanist to settle, but certainly, so far as geological evidence goes at present, they are suggestive, to say the least.

A more interesting case, perhaps, is that of the limestone rooks at Castle Hill, Canterbury, the Weka Pass, and else-

where. Here the well-known coastal fern, Asplenium obtusatum, and the shore groundsel, Senecio lautus, grow abundantly. If such a distribution is correlated with the marine origin of the rocks, then it is evident that species can exist under special conditions for enormous periods of time. It may be pointed out in favour of the fern being a relic that it grows normally on any kind of rock, and even on wet peat, and the limestone can have no special advantage as a spot where the spores could germinate and thrive over any other open rock station.

12. Flowers of the Coastal Plants.

The flowers of the coastal plants are usually not very striking, but this is, indeed, the case with the majority of New Zealand lowland plants. Some, however, are distinctly showy. Samolus repens procumbens in due season spreads white sheets of bloom over the salt meadows, contrasting with yellow masses of Cotula coronopifolia. In the neighbouring marshes and shallow, sluggish streams the flowers of Mimulus repens, of a bright lilac, marked with yellow on the lower lip and throat, are distinctly pretty. Olearia operina, O. insignis, and Senecio monroi would attract attention in any flora, not merely from their handsome flowers, but from the form of their leaves and the contrast of the green with the tomentose surfaces. All the veronicas have a profusion of pretty flowers, and, in addition, those of V. elliptica are very sweetly scented. The white-flowered Gentiana saxosa is very beautiful, trailing over rocks or banks near the sea on some small island in Foveaux Strait, or on the south coast. Where Metrosideros lucida hangs, in the south, over the shore of some land-locked harbour, its myrtle-like leaves dipping almost into the water, the masses of bright-crimson flowers in due season are a glory. The coastal scrub at times is here and there adorned with the drapery of purest white of Clematis indivisa. On bare cliffs of the Marlborough coast hang the long, soft, lilac racemes of Veronica hulkeana, emerging from the foliage of shining green. In the north, according to Mr. H. J. Matthews, the shores of D'Urville Island and Pelorus Sound are decorated in late January with multitudes of the truly lovely flowers of Euphrasia cuneata—white, with a yellow eye, and striped with purple.

Finally, even stations so dasolate as the dunes are enlivened by the large delicate flowers of Calystegia soldanella (white striped with lilac), by the silvery bushes of Pimelea arenaria, the snowy masses of Leptospermum, and the tall, waving, shining plumes of Arundo conspicua.

13. Coastal Distribution as an Aid in defining the Floral Districts.

Up to the present time no attempt has been made to divide the South Island into various floristic small divisions.^* Such are, in fact, very difficult to delimit. This arises from the fact that the Species of wide areas are not known, and can be only guessed at, and also that these smaller divisions must overlap and be likewise in some measure artificial. It seems interesting to inquire whether the distribution of the coastal plants can shed any light on this matter. Such minor divisions may be termed “districts,” just as the three larger have been named “provinces,” the whole of the New Zealand area forming a “region.”

On the south side of Cook Strait the dunes with Spinifex hirsutus, and the cliffs with Coprosma baueri, give a distinctive character to that area. Here, too, are Entelea arborescens, Corynocarpus lœvigata, Veronica speciosa, Euphrasia cuneata, Griselinia lucida, and some other plants which are peculiar to the district or only reach south for a short distance.

Cliffs with a formation of Olearia insignis, Phormium cookianum, and Veronica hulkeana are distinctive of east Marlborough, and that distinction is heightened in comparison with Canterbury by the groves of Corynocarpus lœsvigata, Myoporum lœtum, and Dodonœa viscosa, while on the summits of rocks is Griselinia lucida. The nikau palm (Rhapalostylis sapida), according to Mr. H. J. Matthews, is a feature of the shores of west Nelson. Here, too, is Veronica gracillima. On the volcanic rocks of Banks Peninsula is the fine Senecio lagopus,^† and, at a greater altitude, the beautiful Veronica lavaudiana—this, however, not really a coastal plant. South-west Otago, as mentioned before, is characterized by the coastal thickets of Olearia operina and Senecio rotundifolius, and by the fine Aciphylla intermedia. The shores of Foveaux Strait have the coastal moors before described, with Gentiana saxosa and Euphrasia repens.

From the above, then, it seems clear that the coastal plants and formations are distinctly an aid towards defining the floristic districts of the South Island.

14. Floristic Details.

The pteridophytes and spermaphytes composing the coastal vegetation consist in part of species confined to the coast or

of Norfolk Island has succulent drupes, and Sicyos has barbed fruits.

The endemic element is not nearly so evidently coastal as the foreign. Many of the species are ecologically just as much alpine as maritime plants, and look, indeed, quite out of place on the sea-shore to one acquainted with our alpine vegetation. The endemic Scirpus frondosus is interesting as belonging to an endemic section of the genus, while ecologically it is highly specialised as a sand-binding plant, which characteristic was developed in the absence of grazing animals; and so, notwithstanding its coriaceous texture, it is frequently damaged by those which have been introduced by settlement.

The distribution of the South American element is of some interest, since it shows that so far as the coastal plants are concerned those of subantarctic origin are not confined by themselves to any part of the coast. Of the thirteen species, ten occur abundantly from the north of the North Island to the south of the South Island. Crassula moschata, most abundant and luxuriant in the south, reaches, however, the north shore of Cook Strait. There remain, then, as more or less specially southern or south-western forms, only Carex trifida and Veronica elliptica, and these occur on the east also, at least as far north as Dunedin.

However, this special distribution by no means disproves what has already been stated as to the struggle between the “subtropical” and “subantarctic” elements, because, in the first place, the coast is an unfavourable region for plant-life, and, in the second, all the species except three are also Australian, some having a wide range as well. And the above three species, which are essentially southern in their distribution, are purely subantarctic.

15. Life Forms and Adaptations of the True Coastal Plants.

Special details regarding the life forms of the coastal plants proper are briefly given in the table towards the end of this paper. Here a few general remarks are alone necessary.

A considerable number of the plants are halophytes, and these exhibit more or less the typical succulence of that class. Many have the rush-like habit, and of these Leptocarpus simplex has extremely stiff stems. Sand-binding plants—i.e., those which rapidly grow at the extremities of their shoots as they are being buried, rooting at the same time—are present on the dunes, and exhibit the habit in various degress of intensity. On the salt meadows are turf - forming plants with crowded small leaves and far-creeping stems by which

been the determining factor in change of form. The colour of the shoots of Leptocarpus simplex seems to vary “with the environment, it being dull-green in the salt marsh but more or less red in the drier ground. Calystegia soldanella, as already noted, is prostrate usually, but where a support is available it assumes the climbing habit. Veronica elliptica is usually a tall shrub, but Mr. H. J. Matthews informs me it is a low-growing prostrate plant at West Wanganui Inlet, its most northern habitat. The form of this plant, also, as I have shown (14a; p. 371) is different on the Open Bay Islands from elsewhere on the coast. Senecio lautus is a luxuriant plant with pinnatifid leaves when growing on gravel shores or clay banks, but when on dry rocks its leaves become small and frequently entire. Finally, Cotula coronopifolia has both a land and a water form.

16. Details as to the Inland-coastal Plants.

With regard to those plants which belong also to inland formations, the most important will be dealt with in the special part of this series of papers. But here it must be pointed out that where climatic conditions permit the lowland forest to reach the shore, the coastal plants are much increased in number by many forest plants which are not truly maritime. These not only spread on to the beach, but may occupy rocks which were formerly a part of the mainland. In this latter case the plants are remnants of a former forest, and it is remarkable how some of them, which have no special adaptations, can exist in positions fully exposed to wind and sea-spray. One striking example may be cited. At Jackson's Bay, South West-land, stands on the beach a rock which is an island at high water, but can be approached at low tide. On its summit is a dense growth of Coriaria ruscifolia, Nothopanax arboreum, Coprosma fœtidissima, Veronica salicifolia, Phormium tenax, &c.; while on a covering of peaty soil on the face of the rock, below the above, is a dense mat of the charming liliaceous Enargea marginata, a plant of the forest-floor in certain parts of the North and South Islands and Stewart Island. Leaving out of consideration the above class of plants, there are also true coastal forests—or, more properly speaking, belts of trees and groves, some of whose members are much more frequent on the coast than elsewhere, and many of which perhaps ought to be included amongst the coastal plants proper—at any rate, such are true coastal formations: Myoporum lœtum (Myoporaceœ), Urtica ferox (Urticaceœ), Dodonœa viscosa (Sapindaceœ), Corynocarpus lœvigata (Cornyocarpaceœ). Griselinia lucida (Cornaceœ),

17. Introduced Plants.

As the coastal formations become modified by the action of man through drainage, burning, and so on, and by the trampling of cattle, horses, and other introduced animals, their grazing and manuring, a large number of introduced plants make their appearance even in a formation so antagonistic as a wet salt meadow, and by slow but sure means the indigenous plants are ousted and a new formation comes into being. Such gradual changes are a distinct study in themselves, and must be reserved

for the special part of this series. Likewise, the burning or uprooting of an artificial formation, such as that of Ulex europeus, or Lupinus arboreus on the dunes, is a special case of the same kind, and plants could there gain a footing which would have no chance on an unmodified dune. And this leads the way to the repetition of that great truth which I have stated before, that in a formation where man and introduced animals have never penetrated there are few or no introduced plants. Therefore it is very hard indeed at the present time to estimate what introduced plants have come naturally from the inland modified formations into the coastal region. On the virgin Open Bay Islands, for example, I only noted Poa annua (15). But, however they may have come, there are now a considerable number of introduced plants on many parts of the coast, where the formations are to all intents and purposes primitive. Some of these have been planted to stop the drifting sand—e.g. Ammophila arenaria, Elymus arenarius, Lupinus arboreus, and Mesembrianthemum edule. Ulex europeus and Sarothaninus scoparius of the same formation have escaped in the first instance from hedges.

The following are common everywhere, and some extend to high-water mark on shingly beaches: Hypochœris radicata, Holcus lanatus, Bromus sterilis, Rumex obtusifolius, R. acetosella, œnothera odorata, Trifolium repens, T. arvense, Silene quinquivulnera, Ranunculus sceleratus, Nasturtium officinale, Sagina apetala, Chenopodium album, Senebiera coronopus, Stellaria media, Medicago denticulata, and Glyceria fluitans. But the introduced plants vary much in different parts of the coast, some being confined to limited areas and special conditions, and their names and distribution are quite beyond the scope of an introductory article.

18. Origin of the Coastal Vegetation.

There is no space to inquire at any length into the origin of the coastal vegetation. The fact that nearly all the species can be cultivated easily in ground devoid of salt and far from the seashore^* shows that such plants are little dependent on their special and peculiar environment for their well-being. On the other hand, many garden plants can he grown successfully close to

the sea, even in the most wind-swept localities,^* if they are afforded shelter—i.e., if the wind factor be eliminated. The seeds of many maritime plants are easily capable of spreading inland by various means, and yet there is the comparatively large number (94) of species which are confined exclusively to the coast. All the above points distinctly to the supposition that the coastal plants as a whole occupy their peculiar station not from choice, but from necessity, and that they are ordinary inland plants which have been driven, out of the more hospitable ground by better-equipped competitors. Of course, having finally settled down in a halophytic or psammaphytic station, it goes without saying that such plants would in some instances, in course of time, develop those special adaptations which distinguish coastal plants.

Certain inland xerophytes (see list in Section 16) which commonly grow under coastal conditions owe their position to their xerophytic structure and the abundance of room offered in the open coastal formations for plant-colonists. It is easily conceivable that if certain causes changed the condition of existence for such inland xerophytes, the plants of the coast might be the sole survivors. In this way, too, without any special competition with other plants, coastal species may have originated. Such, in one instance, I have shown to be the case in Chatham Island, where Phormium tenax, formerly a most common plant, is day by day becoming restricted to a few special stations owing to the attacks of domestic animals and drainage (12).

19. Some Differences between North Island and South Island Coastal Vegetation.

Before concluding, a few words seem desirable on certain general differences which exist between the coastal vegetation of the North, and South Islands. As already pointed out, the coastal vegetation proper of the South Island does not commence until parallel 42° S. is crossed, this being, however, a by no means rigid line of demarcation. To the north of this limit the formations are closely related to those of the southern part of the North Island. It is therefore between the vegetation of the northern and southern floristic provinces that a comparison may be drawn, rather than between the two Islands as a whole. These two provinces, even on the coast, are more or less different in many ways, but these differences have a twofold origin, the

one floristic, the otter ecological. These two classes are, however, somewhat closely associated.

The floristic difference is one of genera and species. As for the latter, twenty-seven are peculiar to the North. Island coast, of which some sixteen are confined to the northern province, and it is some of these plants which strongly affect the physiognomy of the vegetation. On the other hand, the peculiar southern plants play a similar rôle.

But the ecological difference is still more marked. This is shown chiefly in the fact that some of the northern formations have a tropical or subtropical stamp, a feature dependent partly on historical and partly on climatic factors, especially rainfall-while the southern bear a subantarctic impress, the result of the very frequent cold south-west gales.

The viviperous mangroves fringing tidal rivers and estuaries, their pneumatophores emerging from the mud; the trunks or Metrosideros tomentosa projecting from the coastal cliffs, densely covered with huge masses of the epiphytic Astelia banksii, looking like a tropical bromeliad; the succulent Peperomia clothing dry banks or rocks; and Entelea arborescens, with its great, thin leaves, are tropical enough, to quote some examples.

On the other hand, the prevailing tone of the southern province, so far as the coast is concerned, and leaving out of the question those edaphic formations common to the two Islands, is distinctly subantarctic. Here stout tussocks, coastal moors, and shrubby growths resembling those of the high mountains form a distinct feature. But even here, on the west more especially, the tropical appearance is not wanting, and, indeed, is striking enough. Freycinetia banksii comes right on to the upper strand, forming the fringe of a truly subtropical forest, ecologically speaking, out of which peep the feathery fronds of tall tree-ferns, and within the dim light of which filmy ferns and luxuriant liverworts abound.

20. List of Coastal Plants Proper, their Distribution and Life-forms.

In the following list the various elements of the coastal flora are thus indicated: A = endemic, B = Australian, C = subantarctic, Cos. = cosmopolitan, whether entirely or confined specially to warm regions. Other elements are indicated by an abbreviated name of the special region, as Nor. I. = Norfolk Island, Polyn. = Polynesian Islands, N. Cal. = New Caledonia, &c. For the New Zealand distribution, 1 = North. Island, 2 = South Island, 3 = Stewart Island, 4 = New Zealand sub - antarctic (Southern) Islands, 5 — Chatham Islands, 6 = Kermadec Islands. The terms used for distribution on the South Island coast speak for themselves.

Bibliography.

[The numbers correspond with references in the paper.]

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