Systematics of the southern African genus Ixia (Iridaceae). 2. The filiform-leaved I. capillaris complex

Abstract

Field study and associated examination of herbarium specimens of the filiform-leaved species of section Morphixia of the South African genus Ixia L. have resulted in an increase in the number of species with this derived leaf type. Ixia capillaris and I. pauciflora have until now been the only species with such leaves and they have not been regarded as immediately related in past accounts of the genus. The two foliage leaves, typically less than 2 mm wide, with a leathery to succulent texture, and lacking a raised central vein or margins, are specialized in the genus. Associated finely fibrous corm tunics, spikes of 1-3 flowers, and when present, short, thread-like lateral branches, usually bearing 1 or 2 flowers, provide supporting evidence that the group is monophyletic. I. capillaris as interpreted until now, comprises four species, three of them new and described here, and the large-flowered I. pauciflora includes two species, one of these described here. While I. capillaris has a branched stem, radially symmetric flowers with a perianth tube (4-)5-7(-8) mm long, tepals 11-15 mm long and thus substantially exceeding the tube, filaments typically exserted 1-2 mm, and anthers (3-)4-5 mm long, I. exiliflora has a tube 8-10 mm long and ± as long as the tepals, included filaments, and anthers 3.5-4.0 mm long. The new I. dieramoides also has included filaments but a perianth tube 13-18(-22) mm long and tepals 11-18 mm long. A third new species, I. reclinata has large flowers with a tube 13-15 mm long, tepals 16-21 mm long, and unilateral, declinate stamens with the filaments exserted 8-10 mm, and anthers 4-5 mm long. Typical I. pauciflora has flowers with unilateral stamens and filaments exserted 2-6 mm from the flower and anthers prominently displayed, but specimens until now included in that species with short, included filaments 3-5 mm long and anthers half included in the tube, are here regarded as I. dieramoides. The I. capillaris group as treated here, now includes five species.