New Zealand has been isolated from other land masses for so long a period that a vegetation has developed which has definite characteristics of great interest. Among these may be noted the large number of endemic species (those found only in New Zealand); the great number of species within certain genera (as species of Olearia); the absence or poor development of genera which flourish in Australia (Acacia); the number of plants with distinctive juvenile and adult forms (Pseudopanax crassifolium); the presence of some plants with affinities to plants in South America, South Africa, and Malaya (Hebe); the large number of hybrids within the genus (Nothofagus)and others; the divaricating growth forms of many coastal plants, as well as those from other habitats, and the cushion-like habit of alpine plants (Raoulia); and the large number of plants which have inconspicuous flowers, small, lacking in colour, and often unisexual (Coprosma). These are some of the main characteristics of the New Zealand flora of which the general aspect is that of large areas of dense forests with evergreen trees, scrub land with manuka, and a profusion of ferns, especially tree ferns.
The New Zealand Botanical Region consists of three principal islands: North Island, South Island, and Stewart Island, which lie between 34° 25' and 47 20' S. It includes also the Kermadec Islands (29° 15' – 31° 24' S) lying some 600 miles north-east of Auckland, the Chatham Islands (43° 35' – 44° 25' S) some 480 miles east of Christchurch, and the subAntarctic Islands, in six widely spread groups between 48° – 55° S and 159° – 179° E. The wide extent of latitude and altitude that is included in this region supports a great variety of conditions for plant growth. About 83 per cent of the species of flowering plants and all species of gymnosperms are endemic. Many of the lower forms of plants are also endemic, including about 35 per cent of the algae and ferns, and many of the liverworts, mosses, and lichens.