This highly variable species is reported to contain diploids, triploids and tetraploids (FNA 8). It is close to punctata (see notes under that name), with occasional intermediates, but it has continued to be distinguished by some authors (D, F, W; Lance 2006; J.B. Phipps in Y). C. collina occurs mostly in east-central states, especially calcareous regions; but it does not extend into Ohio, W.Va. or Md. (FNA 8). Tentatively included here is C. collina var. collicola (Ashe) Palmer, which may represent introgressants with crus-gallii. Var. collicola has been reported from Ky. (F, M); but see note under C. cf. incaedua. The closely related Ozarkian taxon, C. verruculosa Sarg., has been reported from Ky. (F, Gl, M), but plants referred to this name may just represent transitions from collina or punctata to crus-galli (Y). These plants from Ky. or nearby differ from collina in their larger fruit (usually 10-13 mm versus 8-12 mm wide), larger flowers (ca. 1.8-2.3 cm versus 1.5-2 cm wide), with ca. 20 stamens (versus usually 10-15), in larger clusters (?); and vegetative leaves more coarsely toothed, with 2-3 pairs of small lateral lobes (versus finely serrate, usually unlobed). The closely related C. kellermannii Sarg. (?= C. suborbiculata Sarg.) has also been identified in the state (Palmer #23681 at MO); it may represent a hybrid with pruinosa (F).