40 b NORTH AMERICAN FLORA [VoLUME 33 
rous on both sides; body of the fruit narrowly ovate, armed with numerous prickles, covered 
with many glands, finally 1.3-1.5 cm. long and 5-6 mm. thick; beaks straight or slightly 
arcuate, hooked at the apex, not pubescent but the lower part glandular, 3.5-5 mm. long; 
prickles slender, mostly arcuate, more or less reddish-purple, hooked at the apex, glabrous 
except as to small glands below, 4-6 mm. long. 
TYPE LOCALITY: Chemung County, New York. 
DISTRIBUTION: New York. 
ILLUSTRATIONS: Field Mus. Publ. Bot. 4: pl. 2; pl. 7, f. 6; pl. 8, f. 24-26. 
7. Xanthium curvescens Millsp. & Sherff, Field Mus. Publ. Bot. 
Aa 2on. O19: 
Stem branched, becoming reddish, scabrous, about 3 dm. high; leaves about 1 dm. long, 
the petioles and blades subequal; blades deltoid-cordate, weakly 3-lobed, dentate, scabrois, 
punctate with numerous small glandular dots, thin; body of the fruit narrowly cylindric-fusi- 
form, reddish-chestnut or greenish-brown in color, gradually narrowed above, armed with 30- 
50 (or rarely more) prickles, glabrous but punctate with numerous minute glands as are the 
bases of the prickles and beaks, 1.3-1.6 cm. long and 3.5—5 mm. thick; beaks and prickles 
straight below only, strongly arcuate-uncinate above; prickles 3-6 mm. (mostly 4.5-5.5 mm.) 
long; beaks thicker and at times slightly longer, remote and divergent, shortly hispid below. 
TYPE LOCALITY: Orwell, Vermont. 
DISTRIBUTION: Vermont. 
ILLUSTRATIONS: Field Mus. Publ. Bot. 4: pl. 7, f. 7; pl. 8, f. 27-29; pl. 11. 
8. Xanthium leptocarpum Millsp. & Sherff, Field Mus. Publ. Bot. 
432 ) SIG. 
Stems rough above, 3—5 dm. high; leaves 7-19 cm. long. the petioles and blades subequal; 
blades more or less deltoid or 3-lobed, dentate, cordate or subtruncate at the base, scabrous; 
body of the fruit narrowly cylindric-fusiform, chestnut-brown, gradually narrowed above, 
glandular-pubescent as are the bases of the prickles and beaks, 1.3-1.6 cm. long and 3.5—5 mm. 
thick; prickles 18-40, remote, hooked at the apex, 2-3 or rarely up to 4 mm. long; beaks 
remote, arcuate, hooke at dthe apex, thicker and slightly longer. 
TYPE LOCALITY: Burlington, Vermont. 
DISTRIBUTION: Vermont. : 
ILLUSTRATIONS: Field Mus. Publ. Bot. 4: pl. 1; pl. 7, f. 8; pl. 8, f. 30-32. 
9. Xanthium Wootoni Cockerell; De Vries, Sp. & Var. 140. 1905. 
Xanthium commune Wootoni Cockerell, Proc. Biol. Soc. Wash. 16:9. 1903. 
Xanthium oligacanthum Piper, Contr. U. S. Nat. Herb. 11: 551. 1906. 
Stem erect, sometimes with spreading branches, sparsely rough-hispid, 3-6 dm. high; 
leaves 0.8-1.5 dm. long, the petioles equaling or slightly exceeding the blades; blades reni- 
form-orbiculate or deltoid-cordate, obscurely lobed, crenate-dentate, scabrous; body of the 
fruit oblong, in color either stramineous or chestnut or even reddish-brown, gradually narrowed 
above and produced into two (or somewhat rarely three) beaks, armed with 12-30 prickles, 
softly glandular-pubescent as are the bases of the prickles and beaks, 1.1—1.4 (rarely 1.6) cm. 
long and 5-6 (or very rarely up to 7) mm. thick; beaks straight or toward the apex incurved, 
often gaping and exposing the achenes, 3.5—6 mm. long; prickles straight or nearly so but hook- 
ed at the apex, not pubescent except toward the base, equaling the beaks. 
TYPE LOCALITY: Las Vegas, New Mexico. 
DISTRIBUTION: Massachusetts, New Mexico, and Washington. 
ILLUSTRATIONS: Field Mus. Publ. Bot. 4: pl. 7, f. 9; pl. 8, f. 33-36. 
10. Xanthium cenchroides Millsp. & Sherff, Field Mus. Publ. Bot. 
42°30), . 1919. 
Stems more or less punctate with purplish spots running lengthwise, somewhat scabrous 
above; leaves thinnish, dentate, scabrous; body of the fruit ovate, glandular-hispid, 1.5-1.7 
cm. long and 6-7 mm. thick; beaks arcuate, hispid below, glabrate above, hooked at the apex, 
