Trichome Morphology in the Genus Cuphea (Lythraceae)

Trichome morphology of 136 species of Cuphea was studied using light and electron microscopy. Seven different trichome types were recognized, and three were found to have distinct taxonomic value at sectional and subsectional levels. Biarmed trichomes characterize the sections Heteranthus and Amazoniana. Flattened hyaline hairs define a group of species in section Melvilla subsection Pachycalyx. Globose, sessile, glandular trichomes are restricted to sections Archocuphea and Melicyathium. Other types are widely distributed in the genus and can be useful diagnostic characters at the species level. TEM studies of the glandular trichomes revealed subcellular structures thought to be involved in the secretion of resin.