Presence of this taxon in Ky. remains uncertain. C. berlandieri is a variable tetraploid (2n = 36) that is widespread on well-drained fertile alluvium across much of North America (especially along larger rivers), but it is uncommon to absent in most southeastern states (Cr, St, FNA 4, Y). Hybrids with the album group have been reported (FNA 4). The berlandieri group (including buschianum) has seeds clearly roughened with cellular reticulation (when viewed at x 10-20), versus smooth or obscurely roughened in the album complex (including missouriense). They also tend to have more open, slenderly branched inflorescences, with more distinct larger glomerules (ca. 4-7 mm wide versus 3-4 mm), and larger stigmas (ca. 0.3-0.5 mm versus 0.2-0.3 mm). The few plants from Ky. that have been tentatively referred to var. zschackei generally appear intermediate between C. buschianum and C. missouriense, suggesting hybrid origin; these may include colls. from CAMP (KNK) and LEWI (MUR). True var. zschackei is widespread across western and central North America, but perhaps only adventive in eastern states (FNA 4, W). It may be locally frequent in sw. Ohio, but mixed with populations of buschianum (D. Boone, pers. comm.). Seeds of zschackei are smaller (ca. 1.1-1.5 mm long versus 1.5-2.3 mm), with thicker coats; style bases are distinctly yellowed; its leaves are generally less bright green; and plants tend to have an unpleasant odor. Var. boscianum (Moq.) Wahl is a narrow-leaved relative with even smaller seeds that occurs mostly in coastal counties from Tex. to Va.; reports of it from Ky. (M) are probably based on C. standleyanum or C. album var. lanceolatum (see notes under those names).