Broadly defined, T.pusillum is a complex southeastern species (e.g. FNA 26), but there is much variation that probably involves clinal trends and local genetic drift. Appropriate treatment remains uncertain (W); see also notes under the segregate, T. ozarkanum. The few plants mapped here resemble typical pusillum of the Carolina Coastal Plain, which occurs in wooded edges of calcareous wetlands (W). These Ky. records are from swampy woods on calcareous plains and lowlands of south-central counties. The only well-documented large population, with 1000s of plants in the 1980s, is at Meadow Creek Swamp in WAYN, where Quercus phellos is generally dominant. The plants mapped here may be grouped with the taxon named informally as "alabamicum" by S. Farmer in Tenn. and Ala. (W). That taxon is reported to differ from ozarkanum in its elliptic (versus ovate) leaves with more rounded tip; its sepals less narrowed (l/w ca. 2.7-3.1 versus 3-4.3) and generally smaller (ca. 18-25 x 6-8 mm versus 22-30 x 6-11 mm).