Trillium sulcatum Patrick, Brittonia 36: 27–35, f. 1–5. 1984.

Type:— USA. Tennessee: Grundy Co., rich bouldery woods at base of N-facing slope near Deer Lick Falls in Layne Cove, elev. ca. 420 m, western escarpment Cumberland Plateau, 2 km due N of Monteagle, 21 Apr 1980, Patrick, Perkins & Horn 1122 (holotype: TENN!; isotypes: BH, DUKE10000089 digital image!, GH00030175 digital image!, MO-104974!, NCU00000629 digital image!, NY00319900 digital image!, UNA, US 00406395 digital image!) .

Heterotypic synonyms: Trillium erectum var. sulcatum Barksdale, J. Elisha Mitchell Sci. Soc. 54: 280–281. 1938. Type:— USA. North Carolina: Surry Co., in deep woods near Roaring Gap, 27 Apr 1937, Lyons s.n. (holotype: NCU00000625 digital image!; isotypes, NCU00000621 digital image!, NCU00000622 digital image!, NCU00000623 digital image!, NCU00000624 digital image!, NCU00000626 digital image!).

Note:— This name was published without a Latin diagnosis and is thus invalid. The date of collection is given as “1934” on plants.jstor. org, but the specimen labels read 1937.

Trillium sulcatum f. albolutescens T.S.Patrick, Brittonia 36: 30. 1984. Type:— USA. North Carolina: Ashe Co.; rich shady western slopes of “The Peak,” in western part of Ashe County, 16 May 1950, Harper 4167 (holotype: MO-104973!; isotypes: GH00030176 digital image!, NY00319901 digital image!, US 00406185 digital image!).

Notes:— This species is similar to T. erectum but occurs mostly occurs to the west, largely on the Cumberland Plateau in Kentucky, Tennessee and adjacent Alabama. The two are sympatric in a small portion of their distributions in eastern Kentucky, north-eastern Tennessee, south-western Virginia, and north-western North Carolina along the Blue Ridge escarpment of the Southern Appalachians. In some cases, the two species are hard to separate based and may be better regarded as a single variable species with a broad range of variation and similarities in floral fragrance and habitat preferences. However, in cultivation, lower-elevation T. sulcatum is a better garden plant and more vigorous. In the Ridge and Valley of Tennessee, white-flowered forms in uniform populations have been misidentified as T. flexipes, but these forms have dark ovaries and the wet-dog floral fragrance of the typical forms (AF pers. obs.).