This highly poisonous species (with complex alkaloids like others in Melanthiaceae) is widely scattered across east-central states, but common only in some midwestern regions, especially the Ozarks of Mo. (K, Y). In Ky. and Tenn. the few records are clustered in calcareous hills that may have been refuges for mesic forests during past disturbances. Flowering often does not occur, and in Ill. Ebinger (1993) indicated that it may be promoted by fires. In Ky. no response to fire has been suggested, but the population at Mammoth Cave National Park did flower well after unusually dry years in the 1990s (R. Seymour & C. Lapham, pers. comm.). M. woodii is the only North American species of the genus with blackish, purplish or maroon flowers, versus whitish, creamy, greenish or brownish (when dried). Such dark-flowered species may belong to primary divisions within Veratrum/Melanthium (Liao et al. 2007; see also citations of W). This species has often been treated in Veratrum; recent molecular evidence supports distinction of these genera (Kim et al. 2019). In all three Ky. species of Melanthium, 2n = 16 (FNA 26).