ANNALS OF THE MiS l: BiTAIAL MBARI VOLUME 63 1976 NUMBER 1 EVOLUTION, CYTOLOGY AND SUBGENERIC CLASSIFICATION IN MORAEA (IRIDACEAE)' PETER GOLDBLATT2 ABSTRACT Moraea, an African genus widespread south of the Sahara, comprising ca. 92 species, is divided into five subgenera: Moraea, Monocephalae, Visciramosa, Grandiflora, and Vieusseuxia, and into several sections. Chromosome numbers of n = 10, 9, 8, 6, 20, and 12 are reported in the 52 species studied to date. A base number of x = 10 is postulated for Moraea, and Dietes is suggested as the closest living ancestor. Moraea is pictured as having evolved in the mid to late Tertiary in central southern Africa in response to the onset of a dry climatic regime border-ing the tropics. The great radiation of the genus in the southwestern Cape is seen as a more recent phenomenon resulting from the development of a Mediterranean climate in this area. Several nomenclatural changes are made and four new species are described. The problem of infrageneric classification in Moraea was only briefly men-tioned in my recent survey of the chromosome cytology of the southern AfricanIridaceae (Goldblatt, 1971a). In this work the karyotypes of several species weredescribed and discussed with reference to the evolution of the genus, and al-though only a comparatively small number of species were studied, the cyto-logical evidence vwas found to be at odds in many instances with existing sub-generic treatments. Thus it was clear that further cytological investigation wouldprovide invaluable information for taxonomic and evolutionary studies and thatit would be especially useful at infrageneric levels. In preparation for a revision of the South African representatives of Moraea,which comprise the great majority of the species in the genus, I have undertakena more extensive karyotypic study. Chromosomal data are now known for 52species, approximately 70% of the genus, and this information has assisted con-siderably in evaluating the systematics of Moraea because of the strong correla-tions with certain morphological traits. The comparison of morphology and 1 This study was supported by a travel grant from the Council for Scientific and IndustrialResearch of South Africa, and by Grant BMS 74-18905 from the National Science Foundationof the U.S.A. 2 B. A. Krukoff Curator of African Botany, Missouri Botanical Carden, 2315 Tower GroveAvenue, St. Louis, Missouri 63110, U.S.A.ANN. MIssoURI BOT. GARD. 63: 1-23. 1976.