New species, combinations and range extensions in Hesperantha Ker Gawl. (Iridaceae: Crocoideae) from western South Africa

Abstract

The southern and tropical African genus Hesperantha, now with some 88 species, is distinguished in subfam. Crocoideae by the style dividing near or below the mouth of the perianth tube into relatively long style branches and, with a few exceptions, by woody corm tunics. We describe three new species from Northern Cape, South Africa discovered in September 2014. Hesperantha palustris (sect. Concentricae) from marshes at high elevation and Hesperantha filiformis (sect. Concentricae) from rocky sites, were both collected on the Hantamsberg. H. palustris is one of the tallest species in the genus, reaching up to 480mm, with moderate-sized white flowers opening after dark. The diminutive H. filiformis, one of only a few species with just three leaves, has a perianth tube slightly longer than the spreading white tepals. The third new species, Hesperantha eremophila, has the flat-based corm of sect. Hesperantha and is restricted to the Vandersterrberg in the Richtersveld National Park. We also recognize Hesperantha falcata subsp. lutea for populations with yellow flowers opening during the day and closing in late afternoon. Typical plants of H. falcata have white flowers opening in the late afternoon. We also record two range extensions: an additional population of the Roggeveld Escarpment endemic, Hesperantha secunda, from the Keiskie Mtns SW of Calvinia; and high altitude populations of Hesperantha rivulicola from 1 380m on the Hantamsberg, otherwise known from lower elevations near Nieuwoudtville and Calvinia (760–980m).