Stems prostrate and often rooting, to 6 dm or more, short-hairy, especially distally; lvs broadly rhombic-ovate or triangular, irregularly toothed above the cuneate, entire base, 1.5-3.5 נ1-3 cm, glandular-punctate, on petioles 3-15 mm; heads 4-6 mm wide at anthesis; burs 7-9 mm, ellipsoid-fusiform to nearly oblong, slightly compressed, densely glandular, 5-7-ribbed, the ribs bearing 1 or 2 rows of hooked prickles 1-2 mm, the top abruptly invaginated and with an evident rim; 2n=22. A weed in sandy soil and waste places, native to trop. Amer., and intr. n. occasionally as far as Mass. and Oreg.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.