Coreopsis major Walter

Much like no. 5 [ Coreopsis tripteris L.], but smaller, 5–10 dm, vigorously rhizomatous but the stems commonly tufted, the herbage often short-hairy; lvs sessile, the lfls averaging a little shorter, 3–8 cm; outer invol bracts longer and often leafier, sometimes equaling the inner; 2n=26, 78, 104. Mostly in dry, open woods; s. Pa. and O. s. to Fla. and Tex. July–Sept. Most of our plants belong to the widespread var. major, with lfls 1–3 cm wide. The var. rigida (Nutt.) Boynton, with firmer lfls mostly 5–10 mm wide, often in more exposed or less favorable sites, occurs from Va. to S.C. and Ga., but not to the exclusion of var. major; it has 2n=104 and may reflect alloploid introgression from C. delphinifolia Lam., which is itself thought to be an alloploid of nos. 6 [Coreopsis major Walter] and 7 [Coreopsis verticillata L.].