Ixia acaulis, a New Acaulescent Species of Iridaceae: Ixioideae from the Knersvlakte, Namaqualand, South Africa

Abstract

The generic placement of a new spe- cies, Ixia acaulis, from limestone outcrops in the Knersvlakte, Vanrhynsdorp District, South Africa, is not immediately clear in part due to its reduced acaulescent habit. The bright yellow flowers have a subterranean ovary and are borne above ground level on a long perianth tube. An acaulescent habit is unusual in Iridaceae, although known in several genera of the two larger subfamiles, Iridoideae and Ixioideae. In an effort to correctly assign the plant to a genus, we have examined leaf anatomy and chromosome cytology as well as macromorphology and palynology. A basal rooting corm places the species firmly in Ixioideae, as does the perforate exine sculpturing. We conclude that it belongs in the southern African genus Ixia, although an acau- lescent habit is otherwise unknown in this genus and other aspects of the plant do not exactly conform to this genus.