4. Alocasia macrorrhizos (Linnaeus) G. Don in Sweet, Hort. Brit., ed. 3. 631. 1839.
热亚海芋 re ya hai yu
Arum macrorrhizon Linnaeus, Sp. Pl. 2: 965. 1753; Alocasia cordifolia (Bory) Cordemoy; A. grandis N. E. Brown (1886), not Clémenceau (1868); A. indica (Loureiro) Spach; A. indica var. diversifolia Engler; A. indica var. heterophylla Engler; A. indica var. metallica (Schott) Schott; A. indica var. rubra (Hasskarl) Engler; A. indica var. variegata (K. Koch & C. D. Bouché) Engler; A. marginata N. E. Brown; A. metallica Schott; A. pallida K. Koch & C. D. Bouché; A. plumbea (K. Koch) Van Houtte; A. uhinkii Engler & K. Krause; A. variegata K. Koch & C. D. Bouché; Arum cordifolium Bory; A. indicum Loureiro; A. mucronatum Lamarck; A. peregrinum Linnaeus; Caladium indicum (Loureiro) K. Koch; C. macrorrhizon (Linnaeus) R. Brown; C. metallicum (Schott) Engler; C. odoratum Loddiges (1820), not Ker Gawler (1822); C. plumbeum K. Koch; Calla badian Blanco; C. maxima Blanco; Colocasia boryi Kunth; C. indica (Loureiro) Kunth; C. indica var. rubra Hasskarl; C. macrorrhizos (Linnaeus) Schott; C. mucronata (Lamarck) Kunth; C. peregrina (Linnaeus) Rafinesque; C. rapiformis Kunth; Philodendron peregrinum (Linnaeus) Kunth; P. punctatum Kunth.
Pachycaul herbs, massive, to 4 m, evergreen, latex slightly milky. Stem erect, to ca. 1.5 m, decumbent. Leaves several together, clustered at tips of stems in larger plants; petiole to 1.3 m, sheathing in proximal 1/3-1/2; leaf blade light green on both surfaces, ovate-sagittate, bluntly triangular, up to 120 × 50 cm, ± erect, margin entire to very slightly sinuous; posterior lobes 1/3-1/2 length of anterior, somewhat rotund, often overlapping, naked in sinus in mature plants, weakly peltate in juveniles; primary lateral veins ca. 9 on each side of anterior lobe, axillary glands distinct, secondary venation not forming interprimary collective veins. Inflorescences paired among leaf bases, subtended by membranous cataphylls; peduncle barely exceeding cataphylls at anthesis. Spathe 13-35 cm, constricted ca. 1/6 from base; proximal spathe green, ovoid; limb cowl-like at anthesis, later reflexed, then deliquescent, pale yellow, broadly oblong-lanceolate, 10.5-29 cm. Spadix slightly shorter than spathe, shortly stipitate; female zone conic-cylindric, 1-2 × ca. 1.5 cm; pistil pale green, ca. 3 mm in diam.; stigma yellow, sessile, 3-5-lobed; sterile zone slightly equaling female zone, whitish; synandrodes rhombic-hexagonal, ca. 2.5 mm in diam.; male zone whitish, cylindric, 3-7 × ca. 2 cm; synandria 5-9-merous, rhombic-hexagonal, convex-topped, ca. 2 mm in diam.; appendix yellowish, slightly tapering, at least 1/2 length of spadix. Fruiting spathe green, oblong-ellipsoid, ca. 8 cm. Fruit ripening scarlet, ellipsoid, ca. 12 × 8 mm.
Ditches and wet areas of farmlands and wastelands, never away from human disturbance; sea-level to 800 m. S Fujian, Guangdong, Guangxi, Guizhou, Hainan, S Sichuan, Taiwan, S Xizang, Yunnan [originally from tropical Asia; now pantropical].
It is not clear where, if anywhere, Alocasia macrorrhizos occurs wild. It has evidently been prehistorically distributed widely in tropical Asia as a subsistence crop and is now pantropical by introduction as an ornamental.