Cuscuta polygonorum Engelm.

Fls mostly 4-merous, 2 mm, sessile or subsessile in small, dense clusters; cal as long as or longer than the cor-tube, its lobes very obtuse; cor-lobes triangular, acute, erect or ascending, commonly as long as or longer than the tube; styles very short, 0.5–0.8 mm; stigma capitate; fr cupped at base by the persistent cor, depressed-globose, commonly 2–2.5 mm high and 3 mm thick; seeds 2–4, 1–1.5 mm. N.Y. and Ont. to N.D., s. to Tenn. and Tex. On Polygonum and other hosts.