生活型

herb

形態特徵

• Plants annual. Stems erect to ascending or occasionally decumbent, green to red, glabrous to moderately pilose.
• Leaf blades 3.5-5 mm long, 10-20 mm wide, usually lanceolate to narrowly ovate or sometimes ovate, base attenuate, apex acute to acuminate, glabrous to sparsely pilose above and below, margin sinuate to dentate, sparsely ciliate, petioles 6-10 mm long, sparsely to moderately pilose, narrowly winged.
• Peduncles 2.3-5 cm long, 0.5-1 mm in diameter, sparsely pilose. Heads usually radiate, 6-8 mm high, 4-6 mm in diameter. Receptacle 4-5 mm high, 0.4-1 mm in diameter, apex acuminate. Phyllaries 5-6, uniseriate, herbaceous, narrowly to broadly ovate, apex rounded to acute, margin entire to irregularly dentate, sparsely to moderately ciliate. Ray florets 4-7, inconspicuous and only slightly exceeding the phyllaries; corollas 1.8-2.2 mm long, yellow to orange-yellow; tube 0.7-0.9 mm long, 0.1-0.3 mm in diameter; limb 0.9-1.2 mm long, 0.8-1 mm wide, achenes moderately to densely ciliate with straight-tipped hairs, lacking an evident cork-like margin and shoulders; pappus of 2-4 short subequal bristles, 0.3 -0.4 mm long. Disc floret corollas 1.2-1.3 mm long, yellow, 4-merous; tube 0.3-0.4 mm long, 0.2-0.3 mm in diameter; throat 0.8-1.0 mm long, 0.4-0.5 mm in diameter; lobes 0.2-0.3 mm long, 0.2 mm wide; stamens 0.6-0.9 mm long, anthers brown-black; style 0.9-1.1 mm long, the branches 0.3-0.5 mm long; achenes 1.2-1.5 mm long, 0.4-0.6 mm wide, moderately to densely ciliate with straight-tipped hairs, lacking an evident cork-like margin and shoulders; pappus of 2 sub- or unequal bristles, the longer bristle 0.4-0.7 mm long, the shorter 0.2-0.4 mm long.
• In tropics the species prefers wet sand, clay, loam, or gravelly soils especially in disturbed areas along roadsides, cultivated fields, marshes, streams, pastures, meadows, and forests; sea level to 1200 m. Although this species is typically erect and lacks roots at the nodes, under very wet conditions it becomes decumbent and produces nodal roots on lower portions of the stems. </li><li>In Taiwan, <i>A. uliginosa</i> usually prefers growing in slightly, wet loam and gravelly soils along the roadsides, and therefore the stem nodes often bear adventitions roots. The current distributional range in altitude is from 10 to 100 m.</li>

分布

• 台灣 : all the wild populations established are found at Taipei area.
• 世界 : Widespread throughout the tropics, especially in the West Indies, Venezuela, Brazil, Africa, Indonesia, and Malaysia.

引證標本

Taipei: Guandu, May 30, 2006 (Chung, 8999); Nanhai Road, May 25, 2006 (Chung, 9000); Nangang, May 22, 2007 (Chung, 9001) and Sindian, Chungyanghsintsun, January 14, 2004 (Ho, 1692). All the specimens above cited are deposited in the Herbarium of Taiwan Forestry Research Institute (TAIF).

引用文獻

• Shih-Wen Chung, Tien-Chuan Hsu and Yih-Han Chang, Taiwania 52(3): 276-279. 2007.