Xanthium campestre

Xanthium campestre Greene, Pittonia 4: 61. 1899
Stem somewhat scabrous above, often spotted with short purple lines, 5-8 dm. high; leaves 6-17 cm. long including the petioles; petioles almost equaling the blades; blades thickish, subdeltoid, dentate or serrate, not noticeably lobed, truncate or cordate at base, scabrous above, scabrous-pubescent below; fruits very large, for the most part singly disposed, ovoidconic; bodies not often visible among the numerous prickles, becoming about 2.3-2.6 cm. long and 1-1.3 cm. thick; beaks widely divergent, thick and pubescent below, glabrate and slenderly hooked, 6-7 mm. long; prickles terete, arcuate, ferrugineous-hispid below, glabrous above and hooked at the apex, about 5 mm. long; whole fruit (prickles and beaks included) finally 2.8-3.5 cm. long and 2-2.5 cm. wide.
Type locality: Chico, California.
Distribution: California.