Stenactis annuus (L.) Cass.
Annual or biennial herbs. Stems erect, solid, 30-130 cm tall, sparsely pilose, much branched from middle, branches strongly ascending, further ramifying and forming an open corymbiform panicle. Leaves alternate, scarcely pilose on both surfaces, sometimes nearly glabrous, often ciliate with short hairs; radical leaves forming large rosette, ovate to oblong-lanceolate, 3-7 cm×1.5-4 cm, margins dentate; petiole 5-10 cm long; cauline leaves spatulate or lanceolate to oblong-lanceolate, 5-15×2-7 cm, irregularly mucronulate-serrate, apex obtuse-acute; petiole winged almost to base, 3-5 cm long; apex acute, base cuneate to attenuate, short petiole or sessile; radical and lower cauline leaves usually withered and deciduous at anthesis. Heads several to many in terminal corymbs, 5-7 mm long, 10-15 mm across, pedunculate. Involucre hemispheric, bracts 3-seriate, outer bracts ca. 1.5 mm long, inner bracts ca. 3.5×0.5-1 mm, herbaceous, lanceolate, acute, margins scarious. Ray florets many, in 2 rows, tube 1-1.5 mm long; ligule white or tinged purple, linear, 3-5×0.3-0.5 mm, sparsely hirsute below ligule. Disc florets numerous, corolla tubular, narrowly funnelform, 2 mm long, upper part 4 times as long as lower part, 5-lobed, lobes triangular. Achenes oblong-oblanceolate, slightly compressed, 0.7-1 mm long, strigose, ribbed on both sides, pale umber. Pappus of disc florets brownish white, long and short bristles mixed in one row, longer ones to ca. 2 mm. Ray florets without pappus. Fl. Apr-Sep, sometimes Dec-Jan. Chromosome number, 2n = 27 (Peng & Hsu, 1978).
TAIPEI: Shirmen, Peng 6349; Nankang, Peng 11596. TAOYUAN: Paling, Peng 11020. HSINCHU: Taoshan, Peng 8389; Kuanwu, Peng 9361. MIAOLI: Tunglo to Wumeikeng, Peng 11548. HUALIEN: Mukuashan, Peng 7351.
Native of North America. Taiwan, naturalized at low to mid elevations in the north.