Corm Morphology in Hesperantha (Iridaceae, Ixioideae) and a Proposed Infrageneric Taxonomy

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Abstract
The corm tunics of species of Hesperantha vary to a remarkable extent in this African genus in which other morphological characteristics provide little information for classification above the species level. The presumed basic corm type is globose and distinctly asymmetric and has concentric tunics. Globose corms with imbricate tunics, distinctly notched below are believed to be derived while the most specialzed are flat-sided and triangular to companulate in outline, with imbricate tunics, either more or less unbroken below, or notched into segments and often spiny or toothed below. This variation apparently forms a coherent pattern and is emphasized in an infrageneric classification in which other taxonomically useful characters are taken into account. Four sections are recognized. Species with concentric corm tunics are assigned to section Concentrica; those with globose corms and imbricate tunics are assigned mostly to section Imbricata: while most of those with symmetric, campanulate to triangular, flat sided corms with imbricate tunics are assigned to section Hesperantha. A distinctive group with bracts having margins partly united around the stem, and either globose or campanulate corms with imbricate tunics are assigned to section Radiata. A brief survey of the distribution and distinctive species of each section is outlined following the formal taxonomic descriptions.

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