Conyza canadensis var. canadensis
Annual erect herbs. Stems sulcate-striate, 30-150 cm tall, densely or loosely hirsute, branched or not; branches sometimes numerous, strongly ascending. Basal leaves withered at anthesis; middle cauline leaves oblanceolate, apex acute, base attenuate, sessile, few toothed or nearly entire, 5-10 cm long, 0.5-1.5 cm wide, ciliate, more or less strigose on both surfaces; upper leaves gradually reduced, linear to linear-lanceolate, entire, nearly glabrous. Inflorescence a pyramidal panicle, often 1/2 height of plant. Peduncle slender. Heads 3-4 mm long, 2.5-3.5 mm across, numerous. Involucre short cylindric, bracts in 2 or 3 series, linear to linear-lanceolate, herbaceous, outer ones ca. 1 mm long, shorter than inner, loosely hairy or glabrate. Ray florets many, corolla filiform, ligulate, tube ca. 2 mm long, ligule ca. 0.5 mm long, white, tube nearly equalling pappus. Disc florets tubular, ca. 2 mm long; upper part narrowly cylindric, scarcely longer than lower filiform part, 4-lobed, yellowish. Achenes narrowly oblong, 0.6-1 mm long, 0.2-0.3 mm wide, compressed, ribbed on both sides, minutely pubescent, pale umber. Pappus yellowish brown, capillary, bristles 1-seriate, subequal, ca. 2.2 mm long at maturity, persistent. Fl. Jun-Aug.
TAIPEI: Nankang, Peng 11095; Yangmingshan, Peng 13504. TAOYUAN: Yungan, Peng 12770. MIAOLI: Tunghsiao, Peng 11571; Touwu, Peng 3239. NANTOU: Hoshe, Peng 10905. HUALIEN: Tienhsiang, Chen 69.
Native of North America, naturalized in many parts of the world. Taiwan, from sea level to 800 m.