Corrections and Additions to the 'Flora of Tropical East Africa: Convolvulaceae': II: The Identity of Ipomoea mahonii C. H. Wright

Abstract

In 1903 C. H. Wright described an Ipomoea based partly on specimens cultivated at Kew from seeds sent from Uganda, and partly on the collector's description of the shrub from which the seeds were obtained. Dealing with this species for their account of the Convolvulaceae for the 'Flora of Tropical Africa', Baker & Rendle (4(2): 199 (1905) ) state that 'unfortunately no specimens were preserved' and that 'it was described from small specimens raised from seed at Kew, which formed flowers when only 4 inches tall'; they add that 'at present [i.e. in I904 or 1905] the plant is leafless'. Over fifty years later when dealing with the same family for the 'Flora of Tropical East Africa', I also failed to find any type material and repeated the statement that no material could be found. Although I did not suggest any affinity I guessed that it was almost certainly a member of the subgenus Poliothamnus (Hall. f.) Verdc. Recently my attention was drawn to the existence of a separate 'Gardens Herbarium' at Kew and the possibility that specimens of I. mahonii were contained in it immediately occurred to me. This proved to be the case and what can obviously be accepted as a syntype has now been examined, having rested there since 1903 unknown to all workers on the family. It seems strange that Baker & Rendle did not know of its existence since C. H. Wright was surely available to be consulted less than two years later. The identity of the plant proves to be of interest since a name is now available for the variety of Ipomoea hildebrandtii Vatke subsp. grantii (Bak.) Verdc. which I mention in a note on p. 145 of my account. It is not known where Mahon collected his seed but in the early twentieth century Uganda extended to the eastern side of the Great Rift Valley. The variety has distinctive leaves and deserves a name.