This diploid (2n = 28) is widespread in wet woodlands on medium-acid soils across eastern North America, except onthe Gulf Coastal Plain. Variation deserves further assessment. Some Appalachian records mapped here may be transitional to var. elatior; see notes under that name. With the out-moded treatment of F, a coll. from CALL (WKY) was referable to var. linifolia Coleman; and several scattered colls. have been referred to forma tomentosa (Raf.) Pennell. Also, cultivars of Chelone spp. are becoming widely planted, and some appear generally distinct from wild populations in Ky. Plants spread slowy with short rhizomes, making clonal colonies that can easily be divided. Distinction of glabra from obliqua can be difficult (Pennell 1935; FNA 17, W). Its corollas are white or tinged with pink-purple to green (versus pink or reddish-purple throughout); the corolla's "palate" (elevated lower lobe) is usually white-bearded (versus usually yellow); staminodes have green tips (versus usually white). Also, its leaves tend to have longer petioles (mostly 0-1 cm versus 0.5-1.5 cm). C. glabra is one probable parent of obliqua, which has higher chromosome numbers.