In Ky. this species of east-central states is most frequent in thin oak-hickory woods (perhaps with occasional fire), especially on moderately base-rich soils of gentle slopes above calcareous ravines. Plants generally flower in late April to early June, then wither and become dormant;; congeners in Ky flower later and persist until fall. Some colls. from FAYE, HARD, HART, MUHL and elsewhere are relatively hairy. Although these plants may not warrant separate status, it is important to compare them further with similar southeastern species. It is possible that such plants approach T. hirsuticaulis Small, which is a rather indistinct entity that is reported from Tenn., close to Ky. (Ch, K, W). Cultivated plants or garden escapes referred to virginiana are excluded here. Cultivars appear to be largely derived from hybrids with ohiensis, and are sometimes named "andersoniana" (Tucker 1989; FNA 22). T. subaspera also appears to be involved in their parentage (R. Faden, pers. comm.). Hybrids are often reported in the genus, which has rather uniform chromosome numbers; 2n = both 12 and 24 within most species of eastern North America