184 WEEDS AND USEFUL PLANTS. 



It is, however, quite an objectionable weed, on account of the vast quan- 

 tity of its adhesive fruit, in autumn. There appear to be several varie- 

 ties of the plant, noticed in TORREY & GRAY'S N. A. Flora. 



** Akenes slender, linear, 4rsided, beaked at summit, mostly smooth. 



3. B. bipinna'ta, Leaves bipinnately dissected, petiolate, the 

 segments lanceolate or oblong-ovate, mucronate, usually narrowed at 

 base ; heads few-rayed, small, on slender angular-sulcate terminal and 

 axillary peduncles ; outer scales of the involucre scarcely as long as the 

 inner ones ; akenes long and slender, 4-angled and grooved, 3 - 4-awned. 

 BIPINNATE BIDENS. Spanish Needles. 



Plant glabrous. Root annual. Stem 2-4 feet high, quadrangular, branched. Leaves 

 2-4 or 5 inches long, deltoid-ovate in the outline ; petioles 1-3 or 4 inches long. Heads 

 oblong, slender ; rays 3-4, obovate, small, yellow with dark veins ; disk-florets about 20, 



FIG. 125. Spanish Needles (Bidens bipinnata.) 126. A mature akcne, with 4 downward 

 bristly awns. 



