6. Pollia siamensis (Craib) Faden ex D. Y. Hong in K. F. Wu, Fl. Reipubl. Popularis Sin. 13(3): 89. 1997.
长柄杜若 chang bing du ruo
Aneilema siamense Craib, Bull. Misc. Inform. Kew 1912: 415. 1912.
Herbs perennial. Stems erect or ascending, 30--100 cm × 4--10 mm, glabrous or subglabrous. Leaves with petiole 2--4 cm; leaf sheath 2--4 cm, glabrous or sparsely puberulent; leaf blade elliptic to narrowly ovate, 10--25 × 2.5--8 cm, glabrous or subglabrous adaxially, glabrous or nearly so abaxially. Inflorescence nearly as long as distal leaves; peduncle 5--10 cm, densely glandular with short hairs; cincinni numerous, 2--4 cm, usually alternate, sometimes partly in whorls, densely glandular with short hairs; proximal involucral bracts leaflike, but much smaller than leaves, distal ones lanceolate, only ca. 10 mm, densely glandular with short hairs; bracts membranous, often persistent. Sepals ovate-orbicular, boat-shaped, ca. 3 mm, glabrous. Petals white, ovate-elliptic, shallowly boat-shaped, ca. 4 mm. Stamens 6; fertile stamens 3, anterior; staminodes 3, with shorter filaments. Fruit globose, ca. 5 mm in diam. Fl. Apr--Aug.
Forests or humid sandy soils; near sea level to 1200 m. SW Guangxi (Longzhou Xian, Pingxiang Shi), Hainan, S Yunnan [Indonesia, Laos, New Guinea, Philippines, Thailand, Vietnam].
Pollia siamensis has been considered conspecific with P. secundiflora. However, the two species seem distinct in Chinese material.