L., Sp. Pl. 831 (1753).
Derivation: Latin bis, twice; dens, tooth; referring to the two sharp awns of the pappus.
Synonymy: Not Applicable
Common name: None
Annual and perennial herbs; leaves cauline, flat, sessile or petiolate, simple or compound.
Capitula on long peduncles, terminal, in loose cymes or solitary, heterogamous, radiate or the rays absent; involucres campanulate, becoming reflexed in fruit, 2-seriate; outer bracts herbaceous, inner ones with membranous margins; receptacle convex, pitted, with narrow deciduous scales; ray florets uniseriate, sterile, ligulate, few or absent; disk florets numerous, bisexual, fertile, tubular, pentamerous; corolla funnel-shaped; anthers obtuse to slightly sagittate at the base, with a deltoid appendage at the apex; style branches linear, with narrow acute terminal appendages, with hairs on the outer faces.
Achenes linear, compressed; pappus of awns. (E. E. Sherff (1937) Field Mus. Nat. Hist. Botl Ser. 16:1-709.)
About 230 species in tropical and warm temperate regions.
Not yet available