Systematics of Gladiolus and Radinosiphon (Iridaceae) in Tropical Africa and Madagascar

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Iridaceae are a moderately large family of monocots of some 92 genera and 1620 species distributed mainly in the southern hemisphere. One of the few larger monocot families so far investigated in any detail, it is becoming a model example of the patterns of geographic radiation, adaptation, and evolution in the monocots. The proposed research by Dr. Peter Goldblatt of the Missouri Botanical Garden consists of a basic taxonomic revision of the tropical African species of Gladiolus and Radinosiphon. Gladiolus, largest genus of subfamily Ixioideae, comprises some 185 species of which 112 are southern African, ca. 60 occur in tropical Africa and Madagascar, and 20 species are spread through southern Europe, the Mediterranean basin, and Middle East. Neither genus has been thoroughly studied since 1898 and together they constitute the last significant genera of African Iridaceae for which there are no modern synthetic treatments available, this despite the obvious horticultural importance of Gladiolus and considerable confusion over the delimitation of species and their correct names. Field collecting and herbarium study will yield morphological and chromosomal characters useful in species recognition and comparison. Gladiolus is of particular interest geographically as it is one of few genera distributed throughout southern and tropical Africa that has radiated significantly both in the tropics, in temperate southern Africa, and in the winter rainfall area of the southwest coast of South Africa. The establishment of a soundly based taxonomy for the genus will make it possible to compare patterns of evolution over its entire range and to identify centers of endemism and speciation on the African continent.