New Zealand Plants and their Story
The plants having come to New Zealand, having fought many battles, and having in numerous cases given rise to new species, their final settling-down might, at the first glance, seem the work of blind chance. Yet it was nothing of the kind.
A seed falling upon any piece of ground would, if it germinated, depend for its subsistence upon its power to make the best of the circumstances. Were other better-equipped plants present, the species in question would be wiped out. Also, were its structure and organs not suitable for living under the conditions provided, it would soon vanish even were there no competition. In consequence, soil and climate exercise a selective power, and so permit various species of plants to live together under a definite set of conditions. Thus have come into being those collections of plants known as plant societies or associations,* which, taken all together, make up the vegetation of New Zealand. These societies are sometimes quite distinct in themselves, but frequently they merge into one times most peculiar ones, which, depend upon the nature of the rock, its steepness, its exposure with regard to wand and rain, and upon its altitude above the sea. Minor societies frequently exist within the larger ones, and, should certain changes take place, may become dominant.
The two most important groups of plant societies are forests and grass-land. There are numerous varieties of both in New Zealand, and some of them are described further on. Another large class consists of those societies which depend upon the presence of an excess of water in the soil, as in swamps and bogs; while some plants float upon the water of streams or lakes, or are quite submerged. Others owe their presence to the very opposite set of circumstances—scarcity of water; and even in humid, New Zealand something like a desert vegetation may be found in not a few places, but its presence depends rather on the nature of the soil than on an insufficient rainfall. Then there are the societies peculiar to the sea-coast, where salt in the soil and exposure to strong winds are important factors. In such places are sandhills, salt meadows and marshes, shingly or sandy beaches, and cliffs. Rocks have societies of their own, and some-page 13times most peculiar ones, which, depend upon the nature of the rock, its steepness, its exposure with regard to wand and rain, and upon its altitude above the sea. Minor societies frequently exist within the larger ones, and, should certain changes take place, may become dominant.
From what has been said, it can be seen how important a part the study of plant societies plays in the investigation of the botany of any region. Those of New Zealand, unlike those of Europe, temperate Asia, and even much of North America, which have been modified out of all recognition through the long occupation of man, are absolutely primeval even yet in many places. But they, too, are rapidly being modified or destroyed altogether in the progress of settlement. In the temperate regions of the Old World there has been, little chance of studying virgin plant societies; the science of botany began too late for such a work. It is to countries like ours that science looks for such special studies as will bring about that advance in knowledge that will shed light upon the methods by which nature planted the great garden of the world.
* Also called by some "plant-formations," but there is no uniformity as yet in the use of this term.