Bidens
(from bis, twice, and dens a tooth; in reference to the seed). Bur Marigold. ORD. Compositae. A rather large genus of mostly hardy annual and perennial herbs, distinguished by the pericarp having from two to four rigid awns, which are rough with minute deflexed points. Involucre erect, of several oblong, nearly equal, parallel scales. Most of the species of this genus are of no merit as garden plants. Two are natives of Britain, viz., B. cernua and B. tripartita. They thrive in any ordinary garden soil. Propagated by divisions of the plant; or by seeds.
B. atro-sanguinea (dark-bloody). fl.-heads black-crimson, very freely produced. Late summer and autumn. Leaves pinnate. Root tuberous. h. 3ft. Mexico. (B. M. 5227.)
B. ferulaefolia (Ferula-leaved). fl.-heads yellow. Autumn. l. bipinnatifid. h. 2ft. Mexico, 1799. SYN. Coreopsis ferulaefolia. (B. M. 2059.)
B. procera (tall). fl.-heads yellow, large. l. finely divided, deep green. A handsome perennial. h. 6ft. to 8ft. Mexico, 1820. (B. R. 684.)
B. striata (striped). fl.-heads rather large, in a panicled leafy corymb; ray florets white; disk yellow. l. ternately pinnated, glabrous. h. 2ft. to 3ft. Autumn. Mexico. (B. M. 3155.)