Genera Orchidacearum: Volume 2. Orchidoideae (Part 1)

Orchidaceae are the largest monocot family and likely the largest plant family in terms of number of species (ca. 20,000), but for a variety of reasons it remains one of the least understood: lack of a fossil record, relative scarcity of active research until recent years, size and geographical distribution of the family, and the largely tropical distribution of most, which hinders access. The early classifications and generic circumscriptions of Lindley (1830-1840), Bentham and Hooker (1883) and Schlechter (1927) relied mainly on morphological characters, especially floral features. The problem with such reliance on floral features at higher levels of classification is that floral morphology is extremely plastic in evolutionary terms, so that unrelated species may have developed similar structures in response to similar selection, particularly pollinator pressures. Such parallelisms are rife in Orchidaceae, so it is necessary to apply more objective criteria and character choices in