In its broad sense, this species is widely distributed from southeastern states to Central America (FNA 25, W). The colls. mapped here come from sandstone clifftops in MCRE (APSC, KY) and PULA (APSC) They are referable to the relatively glabrous Panicum albomarginatum Nash, which has been combined with tenue in recent treatments. D. tenue in its orginal narrow sense was applied just to hairier plants on the southern Atlantic Coastal Plain (Hitchcock & Chase 1950). A closely related species, D. ensifolium (Bald. ex Ell.) Gould, is known from boggy seeps on the Cumberland Plateau in Tenn., within a few miles of the Ky. border (FNA 25). [A few colls of microcarpon from Ky. and Ind. have been erroneously reported as ensifolium in SERNEC (2023).] Habitat notes from varied treatments and colls. suggest that there may be an eco-morphological sequence from ensifolium on wetter soils, to tenue on mixed or intermediate soils, to albomarginatum on drier soils. Are these taxa distinct or perhaps intergradient? Recent analysis of DNA by Majure et al. (2023) has suggested that a broadened Ensifolia clade may also include leucothrx and longiligulatum, plus other southern taxa; see notes under longiligulatum.