2.
Xanthium spinosum
Linnaeus, Sp. Pl. 2: 987. 1753.
Spiny cocklebur, clotbur, lampourde épineuse
Xanthium ambrosioides
Hooker & Arnott;
X. spinosum
var.
inerme
Bel
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.
2
n
= 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.
