Leaf anatomy and phylogeny of Ixioideae (Iridaceae)

Leaf anatomy is described in Ixioideae, the largest subfamily of Iridaceae, with particular reference to phylogeny and systematics. Leaves in many genera have two rows of opposing vascular bundles (found also in many other Iridaceae), sometimes (except in e.g. Pillansia) combined with typical ixioid features such as a prominent pseudomidrib, mesophyll cells often elongated at right angles to the leaf axis, and epidermal cells also sometimes slightly laterally elongated, frequently with markedly sinuous anticlinal walls, and a single row of papillae per cell. Other characters are limited to a few genera. Anatomical characters are used together with data from other sources to construct a cladogram for the group. Although anatomical characters in general show much homoplasy, the relationships of the existing three tribes, Pillansieae, Watsonieae and Ixieae, diagnosed mainly on the basis of floral and inflorescence characters, are largely upheld by analysis, with at least two potentially useful subtribal groupings within Ixieae.