Introduction

If cloning is the norm among animals and there is no chance for mating, then the earth would be full of the organisms as ‘Dollies’. Similarly in a situation where all plants multiply by simple detachment of parts and growth of each part into a faithful photocopy of the mother plant, then there would be very little room for variation and evolution without which living organisms cannot adapt to unique and changing environments, pests and diseases. Fortunately it is not the case to be. Variety is the spice of life and basic characteristic of life is its unlimited diversity. Nature has myriads of life forms on this planet among which variations are of ubiquitous occurrence. It is particularly so in the megacentres of diversity in the tropics which harbour approximately two-thirds of the biota and where many species of economic importance presumably had their origin. As a matter of fact, variations between individuals of the species were observed over the millennia and were considered as real ‘hot spots’ of evolution.

The notion that no two individuals of a sexually reproducing population are 100% identical prevailed even when methods of scientific scrutiny were not available. In 17th century when the concept of a species was poorly understood, the English naturalist John Ray (1628-1705) showed that within a species there might occur individuals different from the normal in one or more characters. Later Charles Darwin (1809-1882) developed this concept into a supremo and effectively linked the variations with natural selection, survival of the fittest and origin of new species. Down the years, variations among plants and animals had always fascinated an inquisitive mind and helped an evolutionary biologist or a breeder to select a desirable variant or breed a new form of greater agronomic value. Traditional physicians and village doctors of yester years were no different. They collected herbs of certain morphological attributes (of flowers, fruits, leaves etc.) and preferred root drugs of specific colour, smell, size, fibrous content, itching quality etc. obviously from locations known only to them. Even within a medicinal plant species, sometimes one variety was preferred over others. It is also not surprising that curative properties of a plant species change according to seasons or developmental stages and hence vaidyas prefer to collect required plants or their parts during certain periods only (Bharat, 1997).


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