COMPOSITiB 



149 



1. A. trfflda, L. Great Raq- 



1 WEED. 



Annual, stout, 2-10 ft. high, 

 hairy; leaves opposite, all ex- 

 cept the upper deeply 3-lobed; 

 petioles margined. Rich soil, 

 — - a not uncommon weed, espe- 

 cially about dwellings, Man. 

 and westward. 



2. A. pulostachya, DC. Per- 

 ennial RAGWEED. 



Much branched, reclining, 

 and spreading from a creeping 

 rootstock ; leaves opposite, once 

 pinnatifid, the lobes of the 

 upper entire, those of the lower 

 often incised. Dry soil, some- 

 times a troublesome weed, 

 Man.-Alta. 



Fig. 85. — Ambrosia trifida. 



22. XANTHIUM. Cocklebur. 



MoncBcious, the sterile and fertile flowers in different heads, the 

 fertile below the sterile in short spikes; involucre of -the sterile 

 flowers open and saucer-shaped; involucre of the fertile flowers 

 closed, 2-flowered, leathery, and covered with hooked prickles, often 

 2-beaked. Coarse, weedy annuals with large 

 alternate toothed leaves, and producing large 

 bur-like fruit. 



1. X. echinStum, Murr. 



Stem rough, 1-2 ft. high, tinged or spotted with 

 purple ; 'leaves rough, rather hard, obscurely 3 or 

 5-lobed, bluntly dentate and covered with scattered 

 hairs, often glandular beneath; burs two-beaked, 

 usually clustered in the axils, densely covered with 

 prickles; prickles hooked, hairy about half their 

 length; beaks stout, hairy, incurved. Sandy 

 beaches, Man. and Sask. 



Fig. 86. — Xanthium 

 echinatum. 



2. X. glanduliferum, Greene. 



Closely resembling the preceding but the leaves covered with minute 

 projections; bur yellow, not so densely covered with prickles, the pricklea 

 hairy almost to the hook. Dry soil, Man. and Sask. 



