Slender annual, climbing or decumbent, 3–6 dm; lfls mostly 2–5 pairs, seldom more, linear-oblong to oblanceolate or narrowly elliptic, 1–2 cm; peduncles 1–3 cm, with 1 or 2(–4) light purple to white fls 3–7 mm; lowest cal-lobe linear, about equaling the tube, the upper much shorter and triangular; style minutely hairy all around near the tip; fr flat, glabrous, with (3)4(–6) seeds; 2n=14. Native of Eurasia, intr. in fields and waste places from Que. to Wis., s. to Fla. and Tex. May–Aug.