M. Sedgley, J.A. Gardner
Of the estimated 250,000 species of flowering plant found around the world less than 500 are regularly cultivated as crop plants. Many other species are potentially useful, however, and may be collected or cultivated as alternative or supplementary sources particularly in times of shortage. An example of this is the use of chicory as a coffee substitute in Britain and Europe during the years of the Second World War. A noticeable feature of the cultivated crop species is that the majority are native to temperature climates. This the enormous effort which has been invested in agricultural research and development over recent decades. Most of the activity has occurred in the countries of the temperate zone and has concentrated on the species tradionally consumed or utilised in those regions. In the tropical and subtropical areas of the world the pattern has been quite different. With a few notable exeptions, sch as the mango and the banana, the native species have not become major crops on the world market and cultivation is largely confined to local small-scale production. In addition to the cultivated crops there is a tradition of collecting useful commodities from plants growing wild. The tropical and subtropical regions are particularly rich in their range of native species and this is an important resource for the local populations. This wide range of useful wild species in tropical and subtropical areas has received vry little research and development investment, whereas research into traditional temperature crops has resulted in large increases in productivity. The opportunity now exists for the development of alternative crops to improve the range of commodities avilable and so increase the quality of life. The tropical and xubtropical regions, with their range of species with potential are the obvious source of new crops.

This survey is produced by the International Society fo Horticultural Science Working Group on Wild Tropical and Subtropical Plants with Horticultural Potential. The Working Group was established in 1982 in the Commission for Tropical and Subtropiacal Horticulture. It is an international group concerned with all species which are of use to local populations but which may be endangered by genetic erosion. Many plant species in the tropicala and subtropical areas of the world are threatened by habitat destruction and climate changes. The ultimate aim of the working group is to promote awareness and interest in research and conservation of species which are of use mankind. The Working Group has very broad interests both geographically and with regard to the species of interest. As a first step a survey has been conducted to collect information on tropical and subtropical perennials with edible fruits or seeds. It is hoped that in the future it will be possible to collate information on plants with other species uses and life forms. The geographic spread presented in the survey reflects that of the correspondents, and of the genral level of interest in broad international survey of this type. In future, more localised efforts should concentrate on particular areas inmore detail and thus distinguish climatic and cultural boundaries which cannot be delineated in a review of this magnitude. It is hoped that this first step will encourage such future cooperation and activity.

Perennial species have the advantage of providing a food source over a number of years. Some species also have the ability to endure periods os stress due to climate fluctuations. These may provide a food source during adverse conditions when annual crops cannot be cultivated. In such times of hardship, moreover, the tree species may provide an important source of fuelwood. Species which occur regularly in world trade have been excluded as it is the intention of the survey to identify under-exploited species. The members of the working group listed follwoing the survey, have submitted information on species which ae either collected from the wild or cultivated to only a limited extent. This information has been compiled to form the basis of the survey. Three levels of information are presented in the survey. All species identified in the survey are listed alphabetically under families with details of their occurrence in the eight broad geographical regions of the tropics and subtropics. Each region is then treated separately

DOI: 10.17660/ActaHortic.1989.250.6