GENUS 4. 



RAGWEED FAMILY. 



345 



Xanthium echinatum Murr. 

 Fig- 4I34- 



$each Clotbur. 



X. echinatum Murr. Comm. Goett. 6: 32, pi. 4. 1783. 

 X. macuiatum Raf. Am. Month. Mag. 344. 1818. 

 X. oviforme Wallr. Beitr. Bot. i : 240. 1842. 



Stem rough, purplish or purple-blotched, i-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"-n" long, 4"-6" thick, glandular ; prickles 

 very dense, densely hispid from the base to the middle 

 or beyond, subulate, hooked, the longer about 2\" 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. 



4. Xanthium glanduliferum Greene. 

 Glandular Clotbur. Fig. 4135. 



Xanthium glanduliferum Greene, Pittonia 4: 5i. 

 1899. 



Similar to X. echinatum. Leaves very thick 

 and scabrous with short stout papillae; burs 

 oval, 5"-8" long, 3"-4*" 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 Macounii Britton, known only 

 from Lake Winnipeg, Manitoba, differs by a 

 longer bur, 10" long and 4" thick. 



5. Xanthium inflexum Mackenzie & Bush. 

 Missouri Clotbur. Fig. 4136. 



Xanthium inflexum Mackenzie & Bush, Rep. Mo. Bot. 

 Card. 16 : 106. 1905. 



Glabrate, or papillose-roughened above, 3-4i 

 high. Leaves long-petioled, broadly ovate, more 

 or less cordate, mostly 3-lobed, crenate-dentate ; 

 burs i' long or less, the body oblong, more than 

 twice as long as thick, 3"-3i" 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. 

 Sept. 



Aug.- 



