GENUS 4. RAGWEED FAMILY. 
3. Xanthium echinatum Murr. Beach Clotbur. 
Fig. 4134. 
X. echinatum Murr. Comm. Goett. 6: 32, pl. 4, 1783. 
X. macuiatum Raf. Am. Month. Mag. 344. 1818. 
X. oviforme Wallr. Beitr. Bot. 1: 240. 1842. 
Stem rough, purplish or purple-blotched, 1°-2° high. 
Leaves firm, scabrous, with scattered short papillose 
hairs, obtusely toothed and lobed, somewhat resinous- 
glandular beneath; burs commonly clustered in the axils, 
ovoid to oval, 7-11” long, 4’’-6” thick, glandular; prickles 
very dense, densely hispid from the base to the middle 
or beyond, subulate, hooked, the longer about 23” long, 
and about equalling the stout hispid beaks. 
Sea, lake and river beaches, occasionally in waste grounds, 
North Carolina to Nova Scotia, New York, Minnesota and 
North Dakota. Recorded west to Saskatchewan. Aug.-Sept. 
345 
4. Xanthium glanduliferum Greene. 
Glandular Clotbur. Fig. 4135. 
ss glanduliferum Greene, Pittonia 4: 61. 
1599. 
Similar to X. echinatum. Leaves very thick 
and scabrous with short stout papillae; burs 
oval, 5-8” long, 3-43” thick, yellow, the 
prickles scattered, bristly-hispid nearly to the 
hooked apex, scarcely as long as the conic- 
subulate short-bristly beaks. 
In dry soil, North Dakota to Assiniboia, Brit- 
ish Columbia and Nebraska. Adventive in Mis- 
souri. June—Sept. 
Xanthium Macoinii Britton, known only 
from Lake Winnipeg, Manitoba, differs by a 
longer bur, 10” long and 4” thick. 
5. Xanthium infléxum Mackenzie & Bush. 
Missouri Clotbur. Fig. 4136. 
Xanthium inflerum Mackenzie & Bush, Rep. Mo. Bot. 
Gard. 16: 106, 1905. 
Glabrate, or papillose-roughened above, 3°-42° 
high. Leaves long-petioled, broadly ovate, more 
or less cordate, mostly 3-lobed, crenate-dentate ; 
burs 1’ long or less, the body oblong, more than 
twice as long as thick, 3-32” in diameter, glan- 
dular-pubescent; prickles hooked, stiff, longer 
than the diameter of the bur, glandular-pubescent 
below, glabrous above; beaks stout, about 5” long, 
bent at the middle, strongly inflexed, hooked. 
Sandy river-bottoms, Courtney, Missouri. Aug.- 
Sept. 
