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In light of the growing concern over the potentially devastating impacts on biodiversity and food security of climate change and the massively growing world population, taking action to conserve crop wild relatives (CWR), is no longer an option — it is a priority. Crop wild relatives are species closely related to crops, including their progenitors, many of which have the potential to contribute beneficial traits to crops, such as pest or disease resistance, yield improvement or stability. They are a critical component of plant genetic resources for food and agriculture (PGRFA), have already made major contributions to crop production and are vital for future food security; their systematic conservation in ways that ensure their continuing availability for use is therefore imperative. This is a complex, interdisciplinary, global issue that has been addressed by various national and international initiatives. Drawing on the lessons learnt from these initiatives we can now propose a global approach to CWR conservation, the key elements of which are: (1) estimating global CWR numbers, (2) assessment of the global importance of CWR diversity, (3) current conservation status, (4) threats to CWR diversity, (5) systematic approaches to CWR conservation, (6) CWR informatics, and (7) enhancing the use of CWR diversity.

While only about 1-200 species are used intensively in commercial floriculture (e.g. carnations, chrysanthemums, gerbera, narcissus, orchids, tulips, lilies, roses, pansies and violas, saintpaulias, etc.) and 4-500 as house plants, several thousand species of herbs, shrubs and trees are traded commercially by nurseries and garden centres as ornamentals or amenity species. Most of these have been introduced from the wild with little selection or breeding. In Europe alone, 12 000 species are found in cultivation in general garden collections (i.e. excluding specialist collections and botanic gardens). In addition, specialist collections (often very large) of many other species and/or cultivars of groups such as orchids, bromeliads, cacti and succulents, primulas, rhododendrons, conifers and cycads are maintained in several centres such as botanic gardens and specialist nurseries, as are 'national collections' of cultivated species and cultivars in some countries. Specialist growers, both professional and amateur, also maintain collections of plants for cultivation, including, increasingly, native plants. The trade in ornamental and amenity horticulture cannot be fully estimated but runs into many billions of dollars annually and there is considerable potential for further development and the introduction of many new species into the trade. Despite this, most of the collections are ad hoc and no co-ordinated efforts have been made to ensure that adequate germplasm samples of these species are maintained for conservation purposes and few of them are represented at all adequately in seed banks. Few countries have paid much attention to germplasm needs of ornamentals and the Ornamental Plant Germplasm Center in conjunction with the USDA National Plant Germplasm System at The Ohio State University is an exception. Generally there is a serious gap in national and international germplasm strategies, which have tended to focus primarily on food plants and some forage and industrial crops. Adequate arrangements need to be put in place to ensure the long- and medium-term conservation of representative samples of the genetic diversity of ornamental species. The problems of achieving this will be discussed. In addition, a policy for the conservation of old cultivars or 'heritage' varieties of ornamentals needs to be formulated. The considerable potential for introduction of new ornamental species needs to be assessed. Consideration needs to be given to setting up a co-ordinating structure with overall responsibility for the conservation of germplasm of ornamental and amenity plants.

(1995). A global strategy for the conservation of plant diversity. Grana: Vol. 34, No. 6, pp. 363-366.

The problems of world poverty will not be solved by biotechnology alone, nor by traditional plant breeding or improved agronomic practices but by a combination of all of these and other approaches. We need therefore to adopt a broad approach to our considerations of the links between biodiversity, agrobiodiversity and biotechnology.

In most considerations of plant conservation, scant attention is paid to sampling and conserving the chemical diversity and the underlying genetic diversity found in plant populations. Such diversity is of particular importance when dealing with medicinal and aromatic plants where it is precisely their chemical features, such as alkaloids, essential oils, etc. that are the characteristics for which they are valued. In contrast, a great vast amount of effort has gone into isolating and characterizing these chemical constituents from the limited samples that are traditionally used in phytochemical studies. Conservation of the genetic diversity of medicinal and aromatic plants has generally not received a great deal of attention from the genetic resource agencies or national or regional seedbanks1,2, although they are recognized in principle as an important group3,4, nor is there is great deal of evidence from the industry that this has been seriously addressed. Many seed banks do contain samples of some of these plants, but they are not generally the result of deliberate sampling campaigns. Public concern tends to focus on the benefits that may be derived from medicinal plants and on issues of Safety and the assumption is made that the plant resources will continue to be available although no concerted efforts hace been made to ensure this.

Worldwide there are many thousands of species of higher plants which are used by man and can therefore be considered resources (Heywood 1991). About 5,000 species have been cultivated at one time or another and there are many more which are harvested or used directly from the wild. As an illustration of this, the Plant Resources Project of South-East Asia records over 8,000 species in its basic list of species used by mankind in that area (Lemmens et al., 1989) and assuming similar percentages of the floras of other tropical regions are similarly employed, then we can extrapolate to a figure of 25–30,000 species for the tropics as a whole. In addition several thousand species are used by Man in the temperate regions of the world. Up to 25,000 species have been used in herbal medicines and many thousand species of ornamentals are grown in parks and in public and private gardens and as street trees.