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Manual of the New Zealand Flora.
15. Bidens, Tourn
15. Bidens, Tourn.
Annual or perennial usually erect herbs. Leaves opposite, toothed or incised or pinnately divided. Heads corymbosely panicled or subsolitary, on long peduncles, heterogamous and radiate, or homogamous and discoid. Involucre campanulate or hemispherical; bracts in about 2 series, connate at the base, the outer herbaceous, the inner membranous. Receptacle flat or convex, paleaceous. Ray-florets when present female or neuter; ligule white or yellow, spreading. Disc-florets hermaphrodite, tubular, 5-toothed. Anthers usually obtuse at the base. Style-branches of the hermaphrodite florets hairy above, with a long or short subulate point. Achene broad and compressed or slender and tetragonous, often narrowed at the tip. Pappus of 2–4 rigid retrorsely hispid bristles.
A large genus of over 100 species, widely spread in tropical regions, but most plentiful in America. The single New Zealand species is a common weed in all warm countries and many temperate ones.
| 1. | B. pilosa, Linn. Sp. Plant. 832.—An erect glabrous or pubescent herb 1–3 ft. high; branches angular, grooved. Leaves very variable, simple or pinnate; segments 3 or 5, stalked, ¾–2 in. long, ovate or ovate-lanceolate, acute or acuminate, serrate or rarely lobed, thin and membranous. Heads few, terminal on long slender peduncles, yellow, ⅓–½ in. diam.; involucral bracts about; ¼ in. long. Ray-florets few and short, often entirely wanting. Achenes black, slender, 4-angled, striate, crowned with 2 or 4 barbed awns.—A. Rich. Fl. Nouv. Zel. 235; A. Cunn. Precur. n. 442; Raoul, Choix, 45; Hook. f. Handb. N.Z. FL 138; Benth. Fl. Austral. iii. 543; Kirk, Students' FL 318. B. anrantiacus, Col. in Trans. N.Z. Inst. xxvii. (1895) 388.
Kermadec Islands, North Island: Not uncommon as far south as the East Cape. November–March. |