Volume 77 Annals -Number 4 of the 1990 Missouri Botanical Garden PHYLOGENY AND Peter Goldblatt2 CLASSIFICATION OF IRIDACEAE' ABSTRACT A cladistic analysis of Iridaceae, a family of some 1,630 species and ca. 77 genera, and the closely allied Geosiris and Isophysis, both monotypic and sometimes accorded family status, suggests a phylogeny in which there are four major lineages, recognized as subfamilies. Characters used in the analysis include vegetative and floral morphology, anatomy, embryology, pollen ultrastructure, chromosome cytology, and flavonoid and amino acid chemistry. Iso-physidoideae, with a superior ovary, include only the Tasmanian Isophysis. Nivenioideae include the Afro-Madagascan Aristea, three woody Cape genera, the Australasian Patersonia, and Geosiris. The last-mentioned, a saprophyte, restricted to Madagascar, appears to be most closely related to Aristea and is not recognized at the tribal level. Iridoideae have four reasonably well differentiated tribes and a worldwide but predominantly southern distribution. The subfamily is specialized in floral and phytochemical features. Ixioideae, which comprise slightly more than half the total species of Iridaceae, are predominantly southern African and have derived leaf anatomy, pollen exine, flavonoids, and inflorescences. Three tribes are recognized in Ixioideae and four in Iridoideae in both of which some subtribal groupings are suggested. Described formally here are Nivenioideae and Pillansieae. Iridaceae are a relatively large family of petaloid ovary. Isophysis (Fig. 1A) has in the past beenmonocots (Liliiflorae sensu Dahlgren et al., 1985) assigned variously to Isophysidaceae, Hypoxida-comprising over 1,630 species in ca. 77 genera. ceae, or Liliaceae-Melanthioideae as well as toAlthough distributed worldwide, the family has a Iridaceae (Goldblatt et al., 1984). Such is the mor-marked concentration on the southern continents phological distinctness of Iridaceae that there isand the major center of radiation in Africa south virtually no controversy over their status and cir-of the Sahara. Iridaceae are easily recognized among cumscription, except for the treatment of Isophysisthe monocots by having isobilateral equitant leaves, and the monotypic saprophyte Geosiris from Mad-flowers with three stamens, and, with the exception agascar, both of which have been regarded as sep-of the monotypic Tasmanian Isophysis, an inferior arate families (Jonker, 1939). ' Supported by grants DEB 78-10655 and DEB 81-19292 from the U.S. National Science Foundation. I thankJames Walker for encouraging me to undertake this study; Bruce L. Stein for assistance with the cladistic analysis;Paula Rudall, Christine Williams, and B. L. Burtt for their helpful comments on the manuscript and in its preparation;and Margo Branch and John Myers for the original illustrations used here. 2 B. A. Krukoff Curator of African Botany, Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166,U.S.A.ANN. MISSOURI BOT. GARD. 77: 607-627. 1990.