Taxonomy of the genus Keetia (Rubiaceae-subfam. Ixoroideae-tribe Vanguerieae) in southern Africa, with notes on bacterial symbiosis as well as the structure of colleters and the 'stylar head' complex

Abstract

The genus Keetia E.Phillips has a single representative in the Flora of southern Africa region (FSA), namely K. gueinzii (Sond.) Bridson. The genus and this species are discussed, the distribution mapped and traditional uses indicated. The structures of the calycine colleters, and the 'stylar head' complex which is involved in secondary pollen presentation, are elucidated and compared with existing descriptions. Intercellular, non-nodulating, slime-producing bacteria are reported in leaves of a Keetia for the first time. Differences between the southern African representatives of Keetia, Psydrax Gaertn, Afrocanthium (Bridson) Lantz & B.Bremer, and Canthium s. str., which for many years were included in Canthium s.l., are given.