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The Vegetation of New Zealand

Chapter III. — The Autecology of the Coastal Plants

Chapter III.
The Autecology of the Coastal Plants.

1. Lifes Forms.

The coastal trees number 24; all are evergreen. Excepting Corynocarpus laevigata, Metrosideros tomentosa and Sideroxylon novo-zelandicum, none exceed 9 m. in height, 6 m. being the average. The tree-form is generally unsuited to coastal conditions, consequently, in exposed stations or on poor soil, no fewer than 21 of the trees do not develop a distinct trunk but, as shrubs only, blossom and ripen abundant fruit.

The following are the life-forms and the number of specis to each:—canopy-tree 11; bushy-tree 7; rhododendron (tree-composite) form 3; araliad form 2; bamboo-like 1.

The tree-trunks, as a rule, are slender and erect, but in the latter respect some are extremely plastic, e. g. the southern tree-composites, which in response to the frequent gales, develop more or less horizontal trunks whose spread may far exceed the vertical height of the tree. Metrosideros tomentosa, too, growing out of a cliff-face, extends horizontally, but, when page 69its station is ordinary level ground, the trunk is erect (Fig. 19.) though frequently very short indeed, in which case numerous erect branches function as trunks and the form is that of a gigantic shrub. Macropiper excelsun has frequently a much-reduced trunk, but its stems are in a category by themselves, being straight, slender, blackish-purple when young, brownish-purple when mature, marked at distant intervals with leaf-scars and of a bamboo-like appearance. Dysoxylum spectabile, though hardly to be included as a true coastal tree, varies from 5 m. to 15 m. in height and from its trunk and thickest branches are put forth, in winter, pendulous panicles, 30 cm. long, bearing the waxy, white flowers.

The coastal trees owe their, position chiefly to their inability to tolerate frost. Thus, in passing from north to south, they rapidly decrease in number, until, by the time Foveaux Strait is reached, there remains of the northern trees only Myoporum laetum.

The roots of the coastal trees, like those of New Zealand trees in general, often extend semi-horizontally rather than vertically downwards. Frequently they are of great length. The root-systems of Avicennia officinalis and Metrosideros tomentosa have been described in the last chapter.

Coming now to the leaves of the trees, they may be chararacterized as follows: — Evergreen 24, compound 2, simple 22, broad 24, very large1) 6, large 3, medium 15, thin 6, coriaceous 16 (specially thick 6), fleshy 2, glabrous 17 (but 3 hairy only when young), hairy 7 (tomentose beneath 5), glossy 6 (in the case of Coprosma retusa this reaches an extreme degree).


The coastal shrubs number 35, of which 20 are mesophytes, 15 xerophytes or semi-xerophytes, 23 erect (tall1) 13, of medium height 7, of low stature 3), 12 more or less prostrate (truly so 8) evergreen 32, semi-deciduous 1, flat-stemmed more or less leafless 2.

Their life-forms and the number of species to each are as follows: — (a.) erect shrubs 23, consisting: bushy-shrubs 11, divaricating 3, ericoid 5, flat-stemmed leafless 1, rhododendron-form 2, dracophyllum-form (more or less fastigiate and leaves needle-like) 1; (b.) prostrate shrubs 12, consisting of: stout and straggling 4 (all semi-erect), twiggy open cushion 1, divaricating 2 (both open cushions), mat-plants 4 (stems rooting 2), flat-stemmed leafless 1.

1 1) Throughout the autecological chapters the size of leaves is estimated in the following manner: very large = 20 cm. long; large = 10–20 cm. long; medium = 5–10 cm. long; small = 2.5–5 cm. long; very small = less than 2.5 cm. For all the sizes breadth proportional to length is understood, so that the length is decreased or increased according to increase or decrease of the "normal" breadth. What is aimed at is to get a relative idea of the area of the transpiring surface. Evidently these estimates possess no real exactitude, but, as they are estimated in a uniform manner and by one person, they may serve for purposes of comparison, and no more is claimed than this.

1 1) Her? and elsewhere in this book the relative heights of shrubs are denoted as follows: tall, 3 m. and upwards; of medium stature, 1 m. to rather less than 3 m.; of low stature, less than 1 m.

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The stems of most of the shrubs are slender, those of the shrub-composites and Hymenanthera crassifolia being the stoutest. This rock-xerophyte has gnarled, stout stems which, apparently rigid, are really quite flexible and hug the under-lying rock as tightly as possible forming stiff mats or low cushions some 30 cm. deep and 1 m. or so diam. The more or less prostrate shrubs have generally flexible stems, those of Pimelea arenaria (dune-plant) and Coprosma Kirkii1 (rock-plant) being especially so. The wiry, reddish stems of Coprosma acerosa have been already noted. Muehlenbeckia Astoni has stiff wiry, divaricating branches which by interlacing, build on stony shores irregular, rounded cushions 1.5 m. high. The flat, green stems of Carmichaelia Williamsii are 1.2 cm. broad and the shrub may attain a height of 5 m. and be virtually a tree. The prostrate C. Fieldii2), on the contrary, has leafless stems only 2 mm. diam.

Coming next to the leaves of the shrubs, they may be characterized as follows, and to each class is appended the number of species in which it occurs: — simple 33, compound 2 (juvenile Carmichaelia), broad 22, narrow 13 (ericoid 11), large 2, medium 14, small 5, very small 14, thin 5, coriaceous 30 (thick, more or less fleshy 5), glabrous 23, hairy 12 (tomentose 9), glossy 4.

Herbs and semiwoody plants.

The total number of. species of this class is 113 (annuals or biennials 5, perennials 108 — semiwoody 22, herbaceous 86) of which 66 are mesophytes, 47 xerophytes or subxerophytes, evergreen 102, summergreen 6 (excluding annuals &c), spot-bound 66, wandering 57. As for height3), 5 species are very tall, 10 tall, 24 of medium height, 35 of low stature and 39 of very low stature, of which 24 hug the ground or are not more than 4 cm. high.

The life-forms, together with the number of species to each, are as follows: — (1) Annuals or biennials 5, consisting of: erect-branching herb 1 (medium height), erect grass-form 2 (low), prostrate herb 1 (fleshy), moss-like herb 1. (2) Semi-woody plants 22, consisting of: (a.) spot-bound 15, made up of: erect-branching 6, erect tufted 1 (succulent), tufted ferns 2, rush-tussocks 2, prostrate straggling 4 (low mat 1); (b.) wandering 7, made up of: erect-branching 1, prostrate 1, large mat 3, sandbinders 2 (grass 1, herb-like 1). (3) Herbaceous perennials 86, consisting of: (a.) spotbound 46, made up of: erect-branching 3, tufted-ferns 2, tufted grasses 8, tussocks 10 (all grass-form), Iris-form. 2, rosette-form 14 (3 erect, 10 low, 1 straggling), straggling 7 (4 prostrate, 3 semi-prostrate); b. wandering 40, consisting of: erect 8, tufted 2, mat-form 15, turf-making 8, sand-binders 2 (1 minor

1 1) Probably not a species but merely one or two forms of a hybrid group.

2 Although so far only recorded from the coast-line this may probably extend inland, as does Dracophyllum pubescens of the same locality in the Northwestern district.

3 The dimensions used in this book for height of herbs and semiwoody plants are: very tall (over 90 cm.), tall (60–90 em,), of medium height (30–60 cm.), of low stature (15–30 cm.), of very low stature (less than 15 em. to 3 cm. and hugging the ground).

page 71only), Iris-form 1, rosette-form 3 (2 mat-plants also, but included in such), cushion 1.

Coming now to the leaves (1 species leafless), they may be characterized as follows together with the number in each class: — simple 97, compound 15, very large 2, large 9, medium 23, small 33, very small 45, thin 44, coriaceous 39, fleshy or succulent 29, glabrous 89, hairy 23 (tomentose 2).

A few species demand brief mention. Plantago Hamiltonii possesses small, rather broad, thickish, coriaceous, shining-green leaves which overlap forming evenly shaped flat rosettes which grow so close together as to. form a hard turf. Gunnera arenaria, another rosette-plant, makes large circular flat mats. G. Hamiltonii is more striking still with its rosettes over 7 cm. diam. of pale, dull, brownish - green leaves with finely toothed margins, stout midrib and veins and long petiole and its far-creeping, fleshy underground stems 5 mm. diam. It grows very rapidly in cultivation, and seems so perfectly fitted for its moist, sandy habitat (first made known by C. M. Smith) that it is truly remarkable in being one of the rarest species of the New Zealand region. Eryngium vesiculosum of salt-meadow has small rosettes of stiff, prickly, grey lanceolate leaves 10 cm. long and by means of stolons it rapidly forms extensive colonies. Stilbocarpa Lyallii, of coastal scrub in Stewart Island, travels by means of stout hollow stolons 60 to 75 cm. long which arch above the ground. At a certain stage in the growth of a stolon, a young plant is developed at its extremity which will possess 2 to 3 leaves before the young rhizome bent to the ground by the arching of the stolon will have rooted. Extensive colonies many square metres in area of this striking plant with its great bright-green, long-stalked, orbicular-reniform leaves, are formed in this manner, the stolons passing, in some instances, beneath rocks (Fig. 5), so that plants widely a part may be actually in connection.

There is little of special moment to say concerning the stems of the coastal herbs. In general they are slender. Three of the ferns at times build short trunks with a maximum of some 15 cm. in height, but this is in the moist climate of the south. The rhizomes of the sand-binding Desmoschoenus and Spinifex attain an amazing lenght. Urtica australis growing amongst shingle has a thick, woody prostrate stem. Euphorbia ylauca, a dune-herb, has unbranched stems more than 1 m. high, stout, terete and marked on the lower two-thirds with old leaf-scars.

The roots, in many cases bear a distinct relation to the habitat. Those of rock, dune and shingle are frequently of great length, but those of salt-swamp or salt-meadow are usually of medium length. The roots of dune species are often copiously provided with hairs to which the sand clings forming an investing layer. Leptocarpus simplex, as a plant of certain dunes of North Auckland, forms a stout trunk out of its roots and rhizome after the manner of Carex secta, but not nearly so high. In the south this habit seems wanting.

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The coastal lianes, 6 in number (scramblers 4, winder 1, tendril-climber 1), are of little moment, only Ipomaea palmata and Sicyos australis are high-climbing plants, the remainder straggle for a metre or so amongst shrubs, grasses or sedges while Fuchsia procumbens is often prostrate, The stems of the last-named and of Tetragonia trigyna are woody, those of the remainder, though perennial, are herbaceous and that of Sicyos is fleshy, juicy and 6 mm. diam.

Excepting Fuchsia, which is more or less deciduous, the leaves are evergreen, broad and flat. All are thin except those of Tetragonia (fleshy) but those of Angelica geniculata and A. rosaefolia are waxy beneath. The leaves of Sicyos and the last-named are large; those of the remainder are rather small.

Water plants.

There are 7 aquatic spermophytes (6 submerged, 1 subject to tidal change) 4 of which have much branched, thin filiform stems and filiform leaves, 2 have grass-like leaves and far-creeping rhizomes and 1 forms dense matted patches of very slender, creeping and rooting stems, but it is uncovered at low-tide.

2. Pollination.

Apart from the pioneer work of G. M. Thomson (1881 a and b) and a few observations by Cheeseman, Petrie and others, there is little to be learnt from botanical literature regarding the pollination of New Zealand plants, nor have I paid attention to the subject; a virgin field thus awaits cultivation so far as present-day methods of investigation are concerned. Here and elsewhere all that can be supplied are a few statistics and general remarks. Thomson showed that the prevailing belief, as voiced by Wallace1) as to insects being strikingly deficient in New Zealand was not correct and that, though butterflies are few, there are many species of moths represented by numerous individuals while, even at that time, the number of known species of beetles was more than 1300. Above all, Thomson clearly showed what an important part is played by Diptera. Since 1881 thanks to the untiring pioneer researches of G. V. Hudson and his followers, very many more species of insects capable of pollinating have been discovered, so that there is no longer any question as to there being ample for the duty. That some of the species of butterflies have abundance of individuals may be seen by a visit to the montane tussock-grassland on any sunny summer's day. As for pollination by flies, not only are these insects attracted by special unpleasant odours but the cloying scents of certain species (Cordyline australis, spp. of Clematis &c.) bring them in great numbers.

Coming now to the actual coastal species and leaving out of consideration the wind-pollinated Gramineae and Cyperaceae, together with the sub-

1 1) Geograph. distrib. of Animals 1: 457–464 and Darwinism, Ed. 2: 321. 1889.

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aquatics and a few other monocotyledons, 78 (57%) of the remaining 135 species are monoclinous and 57 (43%) are diclinous (dioecious 17 species, monoecious &c. 40 species). Theoretically, about 60 per cent possess flowers conspicuous enough to attract insects and some species with small dull-coloured flowers bear them in such abundance as to be conspicuous or they are visited by insects for their honey and a fair number are sweet-scented. From the horticultural standpoint the above estimate of attractive flowers is far too high, there being at most only 30 species acceptable for gardens and but 3 of these — Xeronema Callistemon, Metro-sideros tomentosa and Hebe speciosa — are of the highest class. As for the colours of the attractive flowers, they are as follows: — white including cream 45, yellow 17, lilac to dark purple 16, reddish to crimson 6, pale blue 1. The estimates given in the first edition of this book for honey flowers (42%) may stand for the present. The flowers of Astelia Banksii, Plagianthus divaricatus and Hebe elliptica are particularly fragrant. No statistics can be given regarding dichogamy, homogamy or methods of pollination but a few special details are presented. Bird-pollination possibly accours in Metrosideros tomentosa. The species of Pimelea are, as a rule, polygamo dioecious, but the plants behave as if truly dioecious. Fuchsia procumbens has hetero-tristylic flowers as in the other New Zealand species; the stamens of the 3 forms do not vary in length. In Selliera radicans (Cheeseman 1877; 542–545) autogamy is impossible and there is perfect correlation between shedding of pollen, trapping of this in the indusium peculiar to the Goodeniaceae and eventual protrusion of the stigma and its pollination by a fly.
3. Dissemination.

Too much stress should not be laid upon statistics derived from the so-called "adaptations" or "contrivances" for travel possessed by fruits or seeds, since it stands out clearly from a fairly close study of New Zealand synecology that it is the community as a whole which moves and not its individuals except in the community itself; in fact with hardly an exception, long-distance journeys for species, except by extremely short stages, appear impossible. Nevertheless, if "contrivances" for wide dispersal are of any moment, coastal plants above all others should afford evidence of such, since so many of the formations are open and some habitats approximate to waste ground — the habitat favourable above all others for plant-colonization. There also comes in the role of the sea as a motive power.

Another matter, often overlooked is, that in a region like New Zealand subject to violent gales, even extremely large seeds can be carried in the open for long distances. When small stones are whirled high into the air, as is frequently the case in exposed localities, there is hardly any seed which cannot be wind-borne for quite a long way; in other words, no plant page 74need be confined to close proximity to its growing-place for lack of locomotive power, but the distance reached is to be measured rather by metres than by kilometres.

As for theoretical capability of long-distance travel, those species with fleshy fruits attractive for birds come first. These number 27 only and but 3 extend throughout both North and South Islands. With regard to the remainder, it is clear that their edible fruits have had little or nothing to do with their distribution, since 1 is confined to one extremely small area, 3 occur only on the Three Kings Islands, 6 exceed only one degree of latitude, or considerably less, and as for the remaining 14 their distribution according to degrees of latitude is: (2°) 1, (3°) 1, (4°) 1, (5°) 1, (6°) 3, 7°) 2, (9°) 3 and (11°) 2. Further, field-observations show that it is wrong to assume that, because a fruit fleshy and even conspicuous, it will be eaten by birds, for many such fruits are never touched — a fact brought home to me through collecting seeds in all the vertical belts for many years and at all seasons.

Those species with fruits or seeds having some special apparatus suitable for wind-carriage number only 23, and these are no more benefited thereby than the species with fleshy fruits, but this matter is further discussed when dealing with the autecology of the other belts and the outlying islands.

4. Seasonal changes.

Speaking of New Zealand generally the distinction between the seasons is far less marked than in the North temperate zone, Deciduous trees &c. are not only very few in number but they play, as a rule, little part in the vegetation and summergreen herbs too are of trifling account. Thus the changes that strike the eye depend chiefly upon blossoming and fruit-ripening. But since so large a proportion of the species produce inconspicuous flowers and fruits, the effect is generally slight and the winter-aspect of forest, heath, tussock-grassland and dune is not strikingly different from that of midsummer. Here as in the other chapters devoted to autecology the matter of flowering receives special prominence, but the treatment is of the briefest. Further, it must be remembered, that the differences in time of blooming are quite considerable in passing from north to south, or in certain parts from east to west so that much latitude must be given to general statements.

From about the end of May to the beginning of August the maximum period of rest is reached by the coastal plants, and in many of the species no growth of any moment is taking place. But even in the middle of June certain plants of a coastal forest may be in bloom in North Island e. g. Wintera axillaris, Dysoxylum spectabile, Coprosma grandifolia and Leptospermum scoparium. The vegetation of salt-swamps and salt-meadows, where frosts are frequent, will be more or less browned, while the aerial page 75parts of Atropis stricta, Scirpus americanus and S. robustus will be dead and those of Salicornia australis partially so. The rounded bushes of Plagianthus divaricatus will have assumed a blacker hue, for then they are either bare of leaves or a few linger in sheltered parts of the shrub. By the end of July, even so far south as Banks Peninsula, Mesembryanthemum australe and Linum monogynum will be coming into bloom on sheltered cliffs. A little later in the north Hymenanthera crassifolia, and Plagianthus divaricatus commence to open their flowers, so that the latter fills the air of the saltmeadow with its honey-like fragrance. In the nor h, too, during September Pittosporum crassifolium, P. umbellatum, Pimelea virgata, Coprosma retusa and C. Kirkii blossom freely. By the beginning of October flowering commences in earnest and the following coastal species bloom that month: Desmoschoenus spiralis, Carex pumila, Ranunculus acaulis, Pittosporum Huttonianum, Entelea arborescens, Angelica rosaefolia, Calystegia Soldanella Myoporum laetum and Senecio lautus. November sees many additions to the flowers, and in the south species which hitherto have bloomed only in the north now flower abundantly, but it is not until December that the salt-meadow of the Eastern district is lit up by sheets of canary-yellow Cotula coronopifolia and white Samolus repens var. procumbens. Mimulus repens growing in shallow water produces in profusion its showy lilac and yellow blossoms, but they are partly hidden by the foliage Atropis stricta, Deyeuxia littoralis and Scirpus maritimus will also be in bloom. On coastal rocks of Queen Charlotte Sound Arthropodium cirrhatum will be a striking feature; in the north it will have been in flower since November. In the South Otago, Fiord and Stewart districts, banks not far from the sea will be draped by Gnaphalium trinerve with its conspicuous bracteate flower-heads. The floral feature of the coast however for the end of this month are the masses of dark-crimson produced by Metrosideros tomentosa in the North and South Auckland and the north of the Egmont-Wanganui districts. Almost as striking is the flowering of Olearia angustifolia and its hybrids with O. Colensoi (= in part O. Traillii), while in the Fiord district the closely-related O. operina is in bloom. Early in January in the Auckland districts the embryos of Avicennia are falling from the trees and a little later are anchored in the mud. During January and February the various coastal species of Hebe will be in bloom and the southern coastal moors be gay with the snowy blossoms of Gentiana saxosa. Many of the plants already mentioned continue to flower, and from this time onwards fruits ripen and seeds are shed. Several coastal species are late flowerers and it is not until April that Olearia angulata, O. albida and Shawia paniculata are in full bloom, but generally speaking, except for such speeies as flower nearly all the year round (Macropiper excelsum, Pisonia Brunoniana) few species blossom after March, though blooms may be produced at unusual times.

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5. Epharmonic modifications.

The striking ecological differences offered by the coastal climate and habitats lead to remarkable epharmonic changes. High winds, strong insolation, salt for above the average in the soil, (it may reach more than 2 per cent according to Aston) and habitats, ranging from extreme mesophytic to extreme xerophytic, demand such modifications in structure and form, if the plant is to live, that its plasticity may be strained to the utmost. Generally there is some life-form of a species which may be called its "usual" form, though this may not represent its most luxuriant state of growth, but in some instances it is not feasible to declare any particular form "usual", more than one form having a claim to that title. In certain cases, the extremes are so distinct, that were it not for the occurrence of intermediates on intermediate habitats, it would be impossible without experiment to decide as to their status. Frequently, too, the matter is complicated by the presence of persistent juvenile forms, hybrids and jordanons.

Properly speaking, any form of a plant, if beneficial, is epharmonic, and the term fits equally the "usual form" and its modifications, indeed, in some localities one or other of the latter may be the sole representative of an epharmonic series. Here the subject under consideration is briefly dealt with under the following heads.

The tree-form and shrub-form.

Most coastal trees under certain circumstances assume a shrub-form, which may be quite as abundant, or even more so than the tree-form. The main factors concerned are frequent winds from the sea and xerophytic habitats.

Metrosideros tomentosa, as a forest tree, may be 21 m. high, but on the bare scoria of Rangitoto Island (S A.) and similar situations it is dwarfed to a small, stiff-stemmed shrub 30 to 60 cm. high which flowers and produces abundant fruit. Pittosporum crassifolium in well-sheltered situations is a bushy-tree some 8 m. high, but its shrub-form is far more common; even in cultivation as a hedge it will flower and fruit when merely 1 m. high or even less. Pseudopanax Lessonii, too, is quite as often a shrub as a tree. In a certain coastal wind-scrub (H. H. Allan, 1926:73) the dimorphic small tree Pennantia corymbosa remains at its juvenile stage as a dense, small-leaved, divaricating shrub.

The prostrate form.

More striking than the common change from tree to shrub is the transformation of these to purely prostrate plants. Thus Myoporum laetum, a small, round-headed tree possessing a distinct trunk, is altogether prostrate on certain little islands to the east of northern Auckland, with its branches far-spreading, cord like and twiggy, and did not epharmonic shrubby forms occur elsewhere — lacking experiment — it would probably be considered a true-breeding variety. Various forms of Coprosma retusa can be seen in clos proximity where a hillside slopes to page 77a stony beach. On rock faces it will hug the rock with far-extending, slender stems; with more shelter on flatter ground it will be a shrub, while on the hillside adjacent there will be the tree-form with a comparatively thick trunk, but its more or less weeping twigs recall those of the prostrate form. This is clear enough from the behaviour of the juvenile when cultivated in good garden soil in a sheltered situation, for it remains prostrate for a considerable time, but finally puts forth erect shoots. The strongly wind-tolerating small tree Dodonaea viscosa, when growing on certain shingly beaches is altogether prostrate and even the still more wind-enduring divaricating shrub, Plagianthus divaricatus, makes a prostrate, close mat on stony shores exposed to strong insolation. The reverse of this may be artifically induced by cultivation in rich, non-saline soil, the divaricating-form being suppressed, a purely twiggy bushy-shrub taking its place.


As for denizens of salt soil generally, a considerable percentage of those on the New Zealand coast are succulent, while, as the statistics for leaves have shown, only those of 40 species are thin out of a total of 108 coastal species. Careful measurements of leaves of 14 species taken by G. Simpson and T. S. Thomson on the shore-line of Otago Harbour — a position far less exposed than when facing the ocean — show in every case increased thickness. The following gives the average increase in thickness for the coastal-form of some of the species: (non-coastal species Blechnum procerum 0.01 mm., Melicope simplex 0.005 mm., Hebe salicifolia var. communis 0.0075 mm., Olearia avicenniaefolia 0.0075 mm., Suttonia australis 0.015 mm., Muehlenbeckia australis 0.0125, Melicytus ramiflorus 0.0075 mm., Pittosporum tenuifolium 0.0125 mm., Polypodium diversifolium 0.01 mm., Cyclophorus serpens 0.07 mm., Asplenium flaccidum 0.01 mm., (coastal species) Myoporum laetwn 0.0275 mm., Hebe elliptica 0.105 mm., Facing the ocean the leaves of Coprosma retusa become twice as thick as when growing inland.


The coastal climate and xerophytic habitats favour reduction in size of leaves or the presence of small-leaved species (70% of the species). Rolled &c. leaves are common in the Gramineae. More interesting is the behaviour of the leaves of Coprosma retusa, which in the prostrate and shrubby forms and on trees where exposed to sun and wind, are comparatively small and rolled, but in the shade are much larger and quite flat.

Contrary to what has just been said, the leaves of certain trees or shrubs on small islands, lying to the east of the Auckland districts, (Rangitoto, Poor Knights &c.) possess leaves much larger than they do on the mainland. T. Kirk (1879: 450 — 452) was the first to point out this unexpected state of affairs and further observations on other islands have both extended the knowledge of the phenomenon and included species in which it is still more marked. The species most concerned are probably Macro-page 78piper excelsum, Melicytus ramiflorus, Suttonia divaricata, Geniostoma ligustrifolium and Myoporum laetum, but Kirk goes so far as to say that the flora of Rangitoto as a whole exhibits "extreme luxuriance of foliage, although its larger members are greatly reduced in stature", and for the Poor Knights I have stated "the arborescent plants exhibit a most remarkable luxuriance of foliage, greater considerably than that of the same species on the mainland" (1906:357). Kirk's explanation of the matter was rather forced and physiologically unsound. As a partial explanation, it may be, that certain of these large-leaved forms are jordanons; indeed, the large-leaved Macropiper excelsum is var. major Cheesem., and this is the sole form of Norfolk Island, the Kermadecs and the Three Kings So, too, the large-leaved Suttonia may not be S. divaricata but a "new" species. At any rate, matters such as this can only be settled by experiment, and opinions based on herbarium material are not only of no value but scientifically dangerous.

Colour changes.

The strong insolation of the coast changes greens into red, orange, brown &c. Thus Tillaea moschata has green shoots in the shade, but in bright light, they are red; the redness of the stems of Leptocarpus simplex increases or decreases according to the strength of the illumination; the green leaves of Cotula pulchella are brown when not shaded. Indeed so potent is exposure to bright light in altering the colour of leaves and stems, that it is a moot point how far the reddish, yellowish or brownish hue of certain dune species — and their colour is of physiognomic moment — may be considered unfixed epharmonic or truly stable under different environments In the so-called "brown" tussock grasses (Poa caespitosa, Festuca novae-zelandiae), which for hundreds of miles colour the landscape in South Island, cultivation in my garden has shown that they may remain green for the greater part of the year.

6. Sand-binders.

Certain species, which can live quite well both on semi-stable dunes and "solid" ground, when subject to a gentle sand-burial, elongate their creeping stems after the manner of true sand-binders (e. g. Arundo conspicua, Poa caespitosa). Possibly Acaena novae-zelandiae var. pallida comes into this category for on dunes it extends its area for several metres, thanks to its far-creeping stem tolerating burial by sand.

7. Turf-making.

Low growing rosette-plants which hug the ground under xerophytic conditions, especially those furnished by what is designated further on "coastal moor", may form a dense turf. Thus the far-creeping Rumex neglectus of stony shore, where its fair-sized leaves rise considerably above the substratum, on coastal moor makes a true turf. Further cases are cited when dealing with the above habitat.

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Exposure to wind, combined it may be with a dry-habitat and strong isolation, leads to the formation of open or dense cushions from certain shrubs, especially those of divaricating-form, e g. Plagianthus divaricatus, the liane Metrosideros perforata, Leptospermum ericoides, Coprosma propinqua and species of Cassinia. Exceedingly common, especially on exposed slopes are dense cushion-like masses of Muehlenbeckia complexa var. microphylla. Wind-borne sand frequently fills the mats of an unnamed coastal variety of Raoulia australis and, growing through the sand, they rise above the substratum as cushions.

Scrambling lianes.

Various coastal species. when growing in the dim light caused by other plants overtopping them, lengthen their stems and become more or less lianoid. The following are examples: Rhagodia nutans, Salicornia australis (up to 1 m. or more), Acaena Sanguisorbae var. pallida, Apium filiforme.

The case of Claytonia.

Claytonia australasica is a plant of great plasticity occurring under various ecological conditions from the coast to the alpine belt. According to H. H. Allan, when growing on loess cliffs in the Eastern district exposed to abundant sea-spray nodules full of starch are developed on its roots.

Forms not specially coastal.

Notwithstanding the moulding action of the coastal conditions there are many true coastal species whose form and structure afford no evidence of proximity to the sea, but these are rather plants of sheltered localities where coastal conditions are absent or much modified, and their presence is to be attributed rather to the mildness of the maritime climate than to any coastal adaptations.