掃帚菊

Annual erect herbs, rarely biennial, tap-rooted, stems terete, 30-120 cm tall, glabrous, sparsely branched or densely branching upward. Leaves grayish green, glabrous, smooth, linear to lanceolate, less than 1 cm wide, almost same width throughout, apex long attenuate to obtuse or rounded, sessile, subamplexicaul, margins entire, leaves on branches reduced, bract-like. Heads ca. 5-6 mm across, in loose racemose inflorescences, scattered or solitary on ascending branches or branchlets. Involucre subcylindric, 5-8 mm tall, 1.5-2 mm across, bracts 4 or 5 seriate, linear-lanceolate to subulate, acute, inner bracts gradually longer, herbaceous. Ray florets pistillate, numerous, ligules white or sometimes pale pink, 2-5 mm long, slightly exserted at anthesis. Disc florets yellow. Pappus longer than tubular part of floret at anthesis, elongate soon after anthesis, 5-6 mm long at maturity. Achenes cylindric, sparsely appressed short hairy, pale brown; pappus soft and fine. Flowering in autumn. Chromosome number, 2n = 18 (Peng & Hsu, 1978).

TAIPEI: Nankang, Peng 11096, Peng 12155 & 13479. TAOYUAN: Lower Paling to Mt. Lalashan, Peng 12105; Tachi, Peng 13501. HSINCHU: Mt. Wuchihshan, Peng 12923 & 12129; Hukou, Peng 7226. MIAOLI: Yuanli, Peng 11115, Peng 11109.

Throughout the temperate northern hemisphere, introduced from North America and naturalized. Now common on waste ground and roadsides in northern Taiwan.