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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.