Review of species limits in Geissorhiza leipoldtii (Iridaceae: Crocoideae) and G. heterostyla with the recognition of new taxa plus important new records in the genus

• Geissorhiza leipoldtii is re-circumscribed to exclude two taxa.
• Geissorhiza ixioides is raised from synonomy as a distinct species.
• Geissorhiza nutans is described as a new species.
• Southern populations of Geissorhiza heterostyla are segregated as subsp. rosea.
• Range extensions are cited for Geissorhiza aspera, G. karroica and G. malmesburiensis.

Field research and herbarium study in the genus Geissorhiza (Iridaceae) has led us to revise the taxonomy of some species. Geissorhiza leipoldtii was previously more widely circumscribed to include G. ixioides as synonym as well as collections that we recognize here as the new species G. nutans. Typical G. leipoldtii has upright to half nodding flowers with a pure white perianth and ascending stamens with longer anthers and usually equal filaments. Geissorhiza ixioides, last collected in 1897 and not again until now, differs in its mauve or pink flowers with a dark centre, short stamens, and short style dividing opposite the middle of the anthers. Geissorhiza nutans stands out in its smaller, nodding flowers with translucent white to pale mauve or pale pink perianth and unilateral, horizontal to drooping stamens with markedly unequal filaments, the upper one half as long as the lower two. We recognize two subspecies in G. heterostyla: subsp. heterostyla with a pubescent stem and nodding, usually blue to violet flowers; and subsp. rosea with a smooth stem and upright to half nodding, white, pale blue or pale mauve flowers. Geissorhiza now includes 102 species, all from the winter rainfall zone of southern Africa. In addition, we document significant range extensions in G. aspera and G. karooica, and report important new records for the critically endangered G. Geissorhiza malmesburiensis. These findings broaden our understanding of the diversity of Geissorhiza and assist in conservation assessments of the species.