This apparently originated from the Mississippi Valley, especially in open riparian vegetation (Cr, W). It may have spread across Ky. after settlement; the earliest records are colls. of C.W. Short in 1835 (PH) from Hamilton Co. Ohio or BOON: "sandy beaches of the Ohio... Hab. Fernbank [near North Bend:; "sand bars of the Ohio River"; and "on roadsides in newly made embankments" However, no other colls. are known from then to the 1930s colls. of B (M). The species is probably much more widespread than the map here indicates. It is close to maculata and distinction can be difficult even with flowers (W, Y); the involucre is cleft on one side for half its length (versus a fourth to third); styles are filiform, 0.5-0.7 mm long (versus clavate, 0.3-0.4 mm); leaves are usually broader in shape (L/W ca. 1.5-2 versus 2-3) and relatively pale green without dark spots; stems often root at nodes (unlike maculata), forming mats up to a meter wide.