Abstract

The quest to describe the diversity of extant plants and the identification of the basic mechanisms that allow them to occupy different environments have shifted scientists’ attention from ancient Greece to the present. This interest was prompted by two fundamental aims: (1) a pressing need to understand the basic functions and growth requirements of plants because they provide direct and indirect services to human kind and (2) the widespread belief that the distribution of organisms was not random, for there was essential order in nature, and that there ought to be a fundamental link between differences in the functions of these organisms and their dominance in contrasting habitats. The notion that differences in plant functions are essential components of their fitness, accounting for their relative dominance in differential habitats, was, therefore, deeply rooted in the minds of early philosophers and, later on, naturalists. While animal functions were relatively easy to embrace from a simple parallel with our own basic functions, those of plants appeared more inaccessible to our ancestors, and the concepts of ‘‘plant’’ and ‘‘plant functions’’ have unfolded through the history of biology.