Plants 10-60(-120+) cm; nodal spines usually in pairs, simple or 2-3-partite, 15-30+ mm. Leaves: petioles 1-15(-25+) mm; blades ± ovate to lanceolate or lance-linear, 4-8(-12+) × 1-3(-5+) cm, often pinnately 3(-7+)-lobed, abaxial faces gray to white, densely strigose. Burs 10-12(-15+) mm. 2n = 36. Flowering Jul-Oct. Damp or seasonally wet, alkaline soils, waste places, margins of agriculture; 10-1000 m; N.B., Ont., Que., Sask.; Ala., Ariz., Calif., Colo., Conn., Del., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Oreg., Pa., R.I., S.C., Tenn., Tex., Utah, Va., Wash., W.Va.; Mexico; Central America; South America; widely established in Old World. Some authors have contended that Xanthium spinosum originated in South America and is introduced and/or naturalized everywhere else that it is found.

Plant: annual; stems < 10 dm, slender, tough; axillary spines < 3 cm, 3-branched, stout, golden Leaves: alternate, short-petioled; blades generally 3-10 cm, linear to elliptic, subentire to pinnately lobed, white-hairy below, gray-green above; base generally 1-veined INFLORESCENCE: primary inflorescence a head, each resembling a flower; staminate heads in clusters, involucre 0, receptacle chaffy; pistillate heads generally 1 (few in upper axils); phyllaries 0 or minute; chaff scales many, spirally arrayed, fused below, free tips spiny, hooked Flowers: Staminate flowers many; corolla translucent; filaments fused, attached to corolla tube base, anthers free; ovary slender; Pistillate flowers generally 2 per head; corolla 0; style branches long Fruit: Fruit: phyllaries 0 or minute; chaff scales many, spirally arrayed, fused below, free tips spiny, hooked; bur cylindric; spines slender; germinating in successive years; pappus 0 Misc: Disturbed areas; < 900 m.