Phylogeny and Classification of Iridaceae

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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. Isophysidoideae, 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 grouping are suggested. Described formally here are Nivenioideae and Pillansieae.