生活型

herb

形態特徵

• Perennial herbs, erect, aromatic, coarse, 1–1.5 m tall, 1.5 cm in diam. at base, much branched, branches densely tomentose; stems conspicuously winged by decurrent leaves.
• Median leaves lanceolate to broadly lanceolate, 6–12×2.5–4 cm, thinly tomentose with viscid glands on both surfaces, apex acuminate, margins serrate, base attenuate, sessile.
• Heads 7–8 mm in diam. when fresh, to ca. 10 mm in diam. when dried, 4–5 mm long, peduncle 5–25 mm long, in compound terminal and axillary corymbs. Involucre hemispheric, bracts greenish-brown, 4- or 5-seriate, outer bracts widely elliptic to widely obovate, acuminate, 1–2×1–1.5 mm, tomentose abaxially, margins ciliate, inner bracts lanceolate to linear-lanceolate, 3–4×0.4–0.6 mm, grading to glabrous. Receptacle flat, glabrous. Outer florets numerous, corolla white, 3–3.5 mm long, 3-lobed; pappus white, slightly longer than corolla. Achenes brown, cylindric, with 5 pale ribs, 0.6–0.8×0.2 mm, with viscid glands. Central florets ca. 50–60, corolla white, purplish toward summit, 2.5–3 mm long, sparingly glandular hairy at base; anthers acute at apex, short tailed at base; anthers and style exserted; achenes vestigial.

物候

Fl. & fr. Mar-Oct.

分布

• 台灣 : Recently naturalized in northwestern Taiwan, in exposed flat areas, riverbed, and swamps, often in large numbers in abandoned rice paddies and grassy fields.
• 世界 : Native of South America and adventive in moist coastal areas of the United States from Florida to Alabama.

引證標本

TAIPEI: Pali, Yen s. n. 1994; Hsichih, Leu 2303; Sanhsia, Leu 2301. TAOYUAN: Luchu Hsiang, Fuhsien, Wang & Lin 1652; Tayuan, Wang et al. 9988. HSINCHU: between Hsinpu and Kuanhsi, Leu 2302; Hsinfeng, Lienhuassu, Yang et al. 4873. MIAOLI: Houlung, Yen s. n.; Tienhuahu, Yen s. n.

參考文獻

• PENG, Ching-I & CHUNG, Kuo-Fang; LI, Hui-Lin, Flora of Taiwan, second edition 4: 1039. 1998.  (Fl. Taiwan 2nd edit.)