岩芋 yan yu

Arum viviparum Roxburgh, Hort. Bengal. 65. 1814 ["viviparium"]; Caladium viviparum (Roxburgh) Nees; Colocasia vivipara (Roxburgh) Thwaites; Remusatia bulbifera Vilmorin; R. formosana Hayata.

Tuber depressed globose, 2-4 × 3.5-5 cm; stolons erect, simple, stout; bulbils ellipsoid, 0.5-2.5 mm, stout; bristles to 1.5 mm, stout. Cataphylls 4 or more, brownish, broad, concealing peduncle, ca. 15 × 3 cm. Petiole 19-42 cm, proximal 1/4 sheathing; leaf blade glossy on both sides, pale green abaxially, green adaxially, oblong-ovate or lanceolate, 11-33 × 7-19.5 cm, sinus 1.5-3 cm; intramarginal vein indistinct. Flowering before leaves develop. Peduncle 6-12 cm. Spathe tube green outside, 3-5 × 1.3-2 cm; limb initially erect, later reflexed, yellow inside, obovate, 5.3-11.5 × 2.5-9 cm, narrowed to base, apex acute, apiculate. Spadix: female zone 1.7-2 cm × 7-9 mm, with 3 or 4 whorls of sterile ovaries at apex and 1 or 2 whorls at base; sterile zone 1.1-2.5 cm, slender, tapering distally; male zone yellowish, clavate, cylindric, 1.5-2.2 cm × 4-7 mm. Fl. Apr-Sep. 2n = 28, 42.

Subtropical forests, epiphytic, on rocks, cliff ledges; 700-1900 m. Taiwan, Xizang, Yunnan [Bangladesh, Bhutan, India, Indonesia (Java), N Laos, Nepal, Sri Lanka, N Thailand, N Vietnam; Africa, SW Asia, N Australia, Madagascar, Pacific islands].

The tubers are poisonous. They are used externally to treat mastitis, traumatic injuries, abscesses, and swellings.