Colocasia

Herbs, wetland [or terrestrial]. Stolons with nodes produced at or near surface; corms underground [aboveground], tuberous. Leaves appearing before flowers, several, clustered apically, erect; petiole usually longer than blade; blade green to dark green or glaucous blue-green adaxially, simple, peltate, ovate- or sagittate-cordate, basal lobes rounded, apex mucronate; primary lateral veins parallel, secondary lateral veins netted. Inflorescences: peduncle erect, shorter than leaves, apex not swollen; spathe tube green; spathe blade orange, opening basally and reflexing apically at anthesis to expose spadix; spadix slender, tapering, usually terminated by sterile appendage. Flowers unisexual, staminate and pistillate on same plant; pistillate flowers covering base of spadix, staminate flowers apical, sterile flowers between pistillate and staminate flowers; perianth absent. Fruits greenish to whitish or red. Seeds 0–5(–35), mucilage probably present. x = 7.

Distribution

Southeastern Asia, 1 species cultivated and escaping in the tropics and subtropics worldwide.

Discussion

Species in the genus Colocasia have received little attention except for C. esculenta, commonly called taro, which is cultivated throughout the tropics and subtropics for its starchy, edible corms. The origin of the cultivated species is uncertain, but all other species in the genus occur in northeastern India and southeastern Asia. Prior to modernization, taro was especially important on the Pacific Islands. Hawaii was a main center of taro cultivation, and the crop played an important role in native culture. About 150 varieties of C. esculenta were developed on Hawaii, including ones those specifically grown for poi, a fermented paste made from crushed, cooked corms (A. B. Greenwell 1947).

Colocasia esculenta was probably brought to the Caribbean and North America from Africa as part of the slave trade. In the southeastern United States, taro was commonly cultivated in the kitchen gardens of slaves and their free descendants (W. Bartram 1791). In the early 1900s, the U.S. Department of Agriculture attempted a campaign to introduce taro as a new root crop in frost-free zones in the southern United States (O. W. Barrett and O. F. Cook 1910). Promotional literature, which included cultivation techniques and recipes for use, was distributed to encourage farmers to try this new crop, but taro was never accepted as a substitute for potatoes (R. A. Young 1936).

Plants of Colocasia esculenta are known by many common names, including taro, cocoyam, dasheen, eddo, malanga, tannia, and others. Many of these same names are also applied to species of Xanthosoma, a New World aroid also cultivated for its starchy corms, which is often confused with Colocasia (see S. K. O’Hair and M. P. Asokan 1986 for a review of edible aroids). Edible taxa in the two genera can be readily distinguished by the peltate leaves in Colocasia and absence of a sterile tip on the spadix in Xanthosoma.

Species 7 (1 in the flora).

Selected References

Matthews, P. 1991. A possible tropical wildtype taro: Colocasia esculenta var. aquatilis. Bull. Indo-Pacific Prehist. Assoc. 11: 69--81.

Wang J.-K. and S. Higa, eds. 1983. Taro, a Review of Colocasia esculenta and Its Potentials. Honolulu.

Lower Taxa

Colocasia esculenta