This globally rare annual is known from scattered midwestern localities, from La. and Miss. to Wis., Mich. and Ont. (K); it is considered threatened, endangered or locally extinct in all states except Mo., where still "vulnerable" (NS). The species is virtually unknown east of the Mississippi Rv. and Ohio Rv., with only rare or dubious reports from Miss. (K), Tenn. (at Fort Campbell; D. Estes, pers. comm.), Ky. and Md. (Pettengill & Neel 2008). In Ky. skinneriana has been reported based on a few colls. made mostly during 1930-1980, but there has been confusion with other species, especially gattingeri (M). It was initially reported by B from EDMO, with verification by Pennell (presumably after 1935), but no coll. has been located. Other tentative records have been rejected (including colls. from HANC and TRIG at EKY); colls. of R. Athey from LIVI and LYON (in his catalog) may still need to be checked. Based largely on Pennell (1935; see also Penskar 2004; and B. Sorrie, pers. comm.), skinneriana can be distinguished from decemloba and other close allies based on its stems with conspicuous scabrellous angles (versus less so to glabrous), its relatively broad, long-tapering leaves ca. 0.6-1.5 mm wide (versus 0.4-0.7 mm), and its relatively large calyx 3.5-5 mm long (versus 2.5-4 mm), stigmas 1.5-3 mm long (versus 1-1.5 mm) and capsules 4-5 mm long (versus 3-4 mm). Typical skinneriana is often mixed with gattingeri in the midwest, but differs in its sparsely branched habit, with a few strongly ascending opposite major branches (versus more spreading alternate branches). Its stems are more strongly angled or ridged (versus terete or nearly so). Its flowers are tubular, very pale pink to white (versus pink-purple), with either very faint spots or lines on the lower lip or none at all. Lower corolla lobes are hairless externally except for marginal cilia (versus hairy externally). It tends to grow in more acid soils, often sandy, and sites are sometimes seasonally damp (xerohydric).