TAXONOMIC IMPLICATIONS OF LEAF ARCHITECTURE IN THE GENUS HIBISCUS

Leaf architecture was investigated in 13 species of the genus Hibiscus . Mature leaves from both fresh and herbarium material were cleared us ing the customary methods, and Hickey's terminology (1973) was used to describe the characters of leaf architecture. In all the species stud ied, the whole lamina was more or less symmetrical, and the major vena tion pattern conformed to the actinodromous perfect, marginal, basal t ype. In all cases, the primary and secondary veins were ornamented wit h parenchymatous bundle sheaths. Imperfectly developed areoles predomi nated over developed ones and their size and shape was variable. The v ein endings were simple, or occasionally, dichotomously branched and t he highest venation order of the family was sixth-degree. Marginal ult imate venation was incomplete. Tracheids were either uni-, or biseriat e, varied in shape and size and were commonly found at the free vein e ndings. Extension cells and isolated tracheids were uncommon. These ch aracters are considered to be of taxonomic importance.