The collection, propagation and culivation of the New Zealand rare and endangered plant species : A thesis submitted in partial fulfilment of the requirements for the National Diploma in Horticulture of the Royal New Zealand Institute of Horticulture (Inc.)

Abstract

It is estimated that approximately 10.0% of the world's vascular plants, which number between 245,000 and 250,000 species, are under threat of extinction or dangerously rare and many may be extinct within twenty years . Conservative estimates are that one plant species is lost from the world every week. In particular, tropical forests alone are probably losing at least one species each day extinct before they are seen by botanists. The situation in New Zealand parallels that of the world. For instance, Given (1981) estimates that between 10.0 and 15. 0% of New Zealand's flowering plants and ferns are currently threatened with extinction. This estimate is in line with the world figure mentioned in the first paragraph. While New Zealand has only about 2,000 species of flowering plants, ferns and fern allies there is concern for the demise of these plants because a very high proportion - over 80% - are endemic. This distinctive feature serves to raise concern stimulated by the most recent checklist of rare plants (Given 1981) which describes 266 species that are at some degree of risk in New Zealand. This writer believes, on the strength of the above evidence, that there is a real need to be concerned for the conservation of New Zealand's threatened plants. Thus, it is the principal purpose of the present thesis to increase our knowledge of the horticultural requirements of this country's rare plants. This is a major, if not essential step in the endeavour to conserve important members of our plant communities.