POLLEN OF NIVENIOIDEAE AND ITS PHYLOGENETIC IMPLICATIONS

Abstract

Phylogenetic analyses clarify the evolution of pollen morphology and its systematic significance in Iridaceae. According to the classification of Goldblatt (1991), the subfamily Nivenioideae consists of six genera: Nivenia (9 spp.), Klattia (3 spp.) and Witsenia (1 sp.) in the southwestern Cape (South Africa), Aristea (ca. 50 spp.) in Africa and Madagascar, Patersonia (ca. 20 spp.) in Australia, and Geosiris (1 sp.), a saprophyte endemic to Madagascar. The first three genera form a monophyletic group with monosulcate pollen and reticulate sculpturing, as in the basal genus Isophysis, which forms its own subfamily. Pollen of Aristea is highly diverse, with plesiomorphic monosulcate types and derived dizonasulculate, trisulcate to spiraperturate and sulculate types, which correspond to three large clades within the genus. The microreticulate, monosulcate type found in Geosiris also resembles the basic type in African Aristea, consistent with its suggested position near the base of the subfamily. The genus Patersonia is unique among Nivenioideae in having inaperturate pollen convergent with that of certain Ixioideae and Iridoideae (Diplarrhena).