This is a southeastern subshrub of damp riparian sites on acid soils (2n = 18), most frequent on the Atlantic Coastal Plain and Piedmont but virtually absent west of the Appalachians (W). It has been combined by some authors with H. apocynifolia Small, which is largely restricted to the Gulf Coastal Plain (W). In Tenn. nudiflorum extends north on the Cumberland Plateau to the headwaters of Big South Fork, close to the Ky. border in Fentress Co. on Darrow Ridge (E. Wofford, pers. comm.) and in Cumberland Co, at the Catoosa WMA (APSC). In Ky., there are old reports from WARR (Pr) and perhaps elsewhere (Short 1840). Short noted "knobs among the barrens" suggesting sphaerocarpum or dolabriforme, a name not used by him at all. The coll. at MO by Pr does appear to be nudiflorum, dated July 1st, 1890, from "near Bowling Green, Warren Co." More recently, nudiflorum has been reported from BALL based on a coll. of R. Athey (#313 at MEM and NCU; BA, M), but that coll. now appears to be lobocarpum (as indicated by M. Brock, pers. comm.). See also notes under adpressum and sphaerocarpon. H. nudiflorum is similar to sphaerocarpon but differs as follows (Y, W): seeds 1.5-1.8 mm long (versus 2-2.7 mm); sepals 1.5-2 mm long (versus 2.5-5 mm); leaves mostly 10-30 mm wide (versus 3-15 mm), with L/W = 1.5-3 (versus 5-15); plants 4-20 dm tall (versus 1.5-6 dm).