A revision of the genus Choritaenia (Apiaceae)

The poorly known monotypic genus Choritaenia (Apiaceae) is revised. Choritaenia capensis is a small annual herb endemic to the central parts of South Africa and has several peculiar morphological and carpological features not found in other genera of Apiaceae. The dorsally compressed, hairy fruits have “inter-rib” wings, and a woody endocarp with globose oil vesicles (rather than vittae or rib oil ducts) at regular intervals in the wings. The very short carpophore is hygroscopic and appears to be an adaptation for dispersal of the mericarps after rain. The phylogenetic position of Choritaenia within the family Apiaceae remains unclear, but it is presumed to be related to the subfamily Azorelloideae, the only group where some members have dorsally compressed fruits with woody endocarps.