The length of the beach thus casually examined is not more than a quarter of a mile long, and no plant mentioned is more than a few yards from high-water mark, the soil being almost pure sand. Imagine some three square miles of country varied by hills and flats of rich soil, with creeks and ravines, precipices and bluffs, dense jungle and thick forest, hollows wherein water lodges in the wet season, and granite ridges, and then endeavour to comprehend the botany of one small island of the tropical coast!
To obtain demonstration of the vitalising and nourishing principles in maritime sands under the effects of heat, light, and moisture, it is necessary to retrace our steps and walk round the sandspit to the transfigured and degenerate mouth of that once mangrove-creek known to the blacks by a name signifying that a boy once tethered in it a sucking fish (Remora). Obstructed by a bank, the creek is dead and dry save when the floods of the wet season co-operate with high tides and effect a breach, to be repaired on the cessation of the rains. No more than four years have passed since the formation of the bank began. It is now a shrubbery made by the incessant and tireless sea from materials hostile, insipid, and loose-sand, shells, and coral debris, with pumice from some far-away volcano. On this newly made, restricted strip one may peep and botanise without restraint, discovering that though it does not offer conditions at all favourable to the retention of moisture, plants of varied character crowd each other for space and flourish as if drawing nutriment from rich loam.
Several botanical Families are represented, the genera and species being:
Casuarina equisetifolia (she-oak)
Avicennia officinalis (white mangrove).
Clerodendron inerme.
Premna obtusifolia.
Vitex trifolia.
Vitex trifolia, var. obovata.
Carapa moluccensis (cannon-ball-tree).
Erylhrina indica (coral-tree).
Sophora tomentosa (sea-coast laburnum).
Pongamia glabra (poonga oil-tree).
Vigna luteola (yellow-flowered pea).
Calophyllum inophyllum (Alexandrian laurel).
Terminalia melanocarpa.
Ximenia americana (yellow plum).
Scoevola koenigii (native cabbage).
Hibiscus tiliaceus (cotton-tree).
Wikstroemia indica. Macaranga tanarius.
Euphorbia eremophilla (caustic bush).
Dodonaea viscosa (hop-bush).
Passiflora foetida (stinking passion fruit).
Ipomea pes caprae (goat-footed convolvulus).
Ionidium suffruticosum, Form A.
Ionidium suffruticosum, Form B (spade-flower).
Blainvillea latifolia.
Gnaphalium luteo-album (flannel-leaf or cud-weed).
Vernonia cinerea (erect, fluffy-seeded weed).
Remirea maritima (spiky sand-binder).
Cyperus decompositus (giant sedge).
Erigeron linifolius (cobbler's pegs or rag-weed).
Tribulus terrestris (caltrops).
Triumfetta procumbens (burr).
Salsola kali (prickly salt-wort).
Mesembryanthemum aequilaterale (pig's face).
Anthistria ciliata (kangaroo-grass).
Paspalum distichum (water couch-grass).
Zoysia pungens (coast couch-grass).
Lepturus repens (creeping wire-grass).
Panicum leucophaeum (pasture-grass).
Andropogon refractus (barbed wire-grass).
Tragus racemosus (burr-grass).
Eragrostis brownii, var. pubescens (love-grass).
With the exception of some of the grasses and two noxious weeds, this assemblage is representative of plants which grow just beyond the sweep of the waves, and are prosperously at home nowhere else. One, the cannonball-tree, is so highly specialised that its presence is but temporary, for it endures but a single set of conditions—saline mud and the shade of mangroves. The thick, leathery capsule contains several irregularly shaped seeds, somewhat similar to Brazil nuts, but larger in size and not to be reassembled readily after separation. When stranded, germination is prompt, but the young plants, lacking essential conditions, invariably perish. One of the trailers—the caltrops—has trilobed, saw-edged leaves (harsh on both sides), yellow flowers of unpleasant odour, and fruit which, perhaps, formed the model of the war weapon of the time of the Crusaders. In whatever position it rests on the ground it presents an array of spikes to the bare foot. Though all its superficial qualities are graceless, it performs the admirable office of binding sand, and thus prepares the way for benign and faultless vegetation.
That his garden might not only be instructive but profitable to mankind, Neptune heaved on to its verge three coco-nuts, the goose-barnacles on two of which bore testimony to a long drift. That which retained the germ of life fell into the hands of a visiting black boy, who split it open to feast on the pithy and insipid “apple” within its shell at the base of the sprout. This mischance ruined for the time being the prospect of a fine effect; but the perseverance and prodigality of Neptune none may estimate. He will certainly bring from distant domain another nut which may escape the observation of the never-to-be-satisfied black boys until the young plant itself has assimilated its concentrated food, and begins to spread its glossy fronds in the face of the sun. In the meantime the garden displays four weeds, two of the nature of pests, two of discomfort merely; ornamental, scented, and flowering shrubs, and trees promising to be conspicuous and picturesque, so that credit is to be divided—the sea made the site, the adjacent land provided all the becoming plants.
What are the elements in this primitive spot which afford nutriment to vegetation of such varied character? Probably there are few of the beaches of islands within the Great Barrier Reef on which the majority of the plants do not exist. It is typical, therefore, not of isolated experiments on the part of Nature, but of conditions and processes repeated in similitude wheresoever in the region raw sand heals the wounds inflicted by the sea or the grumbling sea retreats before the sibilant, incessant sand.