The leaf anatomy of Crocus L. (Iridaceae-Ixioideae) is described in the context of the systematics of the subfamily. Leaves of most species have a distinctive cross-sectional outline, with a central square or rectangular 'keel', and two lateral 'arms'. C. carpetanus differs markedly in that it lacks a single central keel, and has several surface ridges. Other minor variations include the presence of sclerenchyma 'girders' in some species, absent in others, which may be taxonomically significant.