This has a largely midwestern range, and is largely restricted to mesic woods on base-rich soils (FNA 26). In early work on the flora of Ky. (M), flexipes was confused with T. erectum or with the northeastern species, T. cernuum L. In the central Bluegrass, Short (1928-9) found so-called "erectum" only in "rich, secluded woodlands." Populations vary much in flower color (from all white to mixed to all red). Many widely scattered colls. are referable to the reddish or purplish forma walpolei (Farw.) Fern., and intermediates also occur. However, hybrids with erectum or sulcatum have been documented as well (FNA 26), and some of these have also been named forma walpolei. Moreover, some plants otherwise referable to flexipes have more or less erect pedicels (R. Cranfill, pers. comm.; see also diverse horticultural websites). A thorough assessment of variation among these taxa has yet to be published.