152 



THE INDiANA WEED BOOK. 



dark green, whitish woolly beneath; axils each with a short-stalked, 3- 

 pronged, yellow spine nearly 1 inch long. Bur oblong-cylindric, £ inch 

 long, hairy and with 1 or 2 short, awl-shaped beaks and numerous short 

 hooked spines. (Fig. 112.) 



This cocklebur has invaded Indiana from, the south, where it is 

 very troublesome, and is- recorded from a number of the southern 

 counties. Aug.-Oct. It is one of the most spiny of the American 

 weeds, and the hooked spines on its burs provide for wide distribu- 

 tion by every- passing animal. It is a native of tropical America 

 and, unlike the other cockleburs, occurs mostly in grass-land, as 

 pastures, meadows, and along roadsides, spreading even in strong 

 sod. The two seeds in the thick-walled bur retain their vitality 

 for yedrs and care should be taken to destroy the first plants which 

 appear before the burs mature. Remedies: mowing several times 

 in late summer ; deep cutting with hoe or spud in May and June ; 

 thorough cultivation for two or three successive seasons. 



117. Xanthium giabratum DC. Common Cocklebur. Glotbur. (A. N. 1.) 

 Erect, rough, branching, 1-6 feet high ; leaves heart-shaped or ovate, 

 long-stalked, the lower often 8 inches wide, margins toothed or lobed; 

 axils without spines. Burs oblong, nearly glabrous, J inch long, with 2 

 straight 2-toothed beaks and numerous smooth hooked spines. (Figs. 1', 

 o; 113.) 



Abundant everywhere in rich cultivated soils, barnyards, waste 

 places and along roadsides. Aug.-Oct. 

 One of the worst of corn-field weeds in 

 river bottoms, and in pastures especially 

 annoying in wool and the manes of 

 horses. The burs with their two en- 

 closed seeds are widely distributed over 

 lowlands by annual overflows, and on 

 the uplands by animals to which they 

 closely adhere. It is said that only one 

 of the 2 seeds will germinate the first 

 season, the other lying dormant for a 

 year. Another species, the American 

 cocklebur or hedgehog burweed (X. 

 canadense Mill.) is known from central 

 Indiana and probably occurs over most 

 of the State. It differs in having the 

 burs somewhat hairy or glandular with 

 the beaks hooked or incurved. Rem- 

 (After Dewey./ edips . th.or.ough cultivation; pulling be- 



fore the burs are formed ; burning mature plants before plowing. 



Fig. 113. 



