Description from Flora of China
Eriocaulon cantoniensis Hooker & Arnott; E. pterosepalum Hayata; E. sinicum Miquel; E. sinii Ruhland; E. wallichianum Martius.
Leaves linear, 10--35 cm, 4--13 mm wide at middle, veins 15--37. Scapes 5--20, 20--60 cm, 4--6-ribbed; sheath 4--12 cm; receptacle glabrous; heads subglobose, ca. 6.5 mm in diam., glaucous, base truncate; involucral bracts straw-colored, obovate, 2.2--2.4 mm in diam., rigid, abaxially white clavate hairy; floral bracts obovate to obovate-cuneate, 2--2.5 mm, abaxially hairy toward apex. Male flowers: sepals spathelike, glabrous, laterally winged, apex (2 or)3-lobed or occasionally truncate; petals (2 or)3, linear, apex pubescent, gland usually indistinct; anthers (4--)6, black. Female flowers: sepals (2 or)3, free, glabrous, posterior one smaller than others, sometimes reduced or absent, wingless, lateral ones boatlike, winged; petals (2 or)3, linear, unequal, membranous, occasionally villous at center, apex white clavate hairy; ovary (2 or)3-loculed; style (2 or)3-cleft. Seeds ovoid, 0.6--0.7 mm; testa hexagonally reticulate, prickles 1 per cell, T-shaped. Fl. and fr. Aug--Mar.
The 2-merous form that is occasionally found in China resulted in the 2-merous Eriocaulon willdenovianum Moldenke ( E. longifolium Nees ex Kunth (1841), not Rafinesque (1840)) being put in synonymy under E. sexangulare in FRPS. These two species are distinct outside of China, and it is possible that the 2-merous plants in China represent a reduction from 3-merous to 2-merous within E. sexangulare. This question needs further study.
Ponds, rice fields; near sea level to 800 m. Fujian, Guangdong, Guangxi, Hainan, Taiwan [Cambodia, India, Indonesia, Japan, Laos, Malaysia, Myanmar, Philippines, Sri Lanka, Thailand, Vietnam; Africa (including Madagascar)].