Xanthosoma

Xanthosoma is a genus of about 50 species of tropical and sub-tropical arums in the flowering plant family, Araceae, all native to tropical America. Several species are grown for their starchy corms, an important food staple of tropical regions, known variously as malanga, new cocoyam, tannia, tannier, yautía, macabo, taioba , dasheen and ‘ape. Many other species (including especially X. roseum) are utilized as ornamental plants, and in popular horticultural literature are known as ‘ape or elephant ear (from the purported resemblance of the leaf to an elephant's ear), although the latter name is sometimes also applied to members with similar appearance and uses in the closely related genera of Caladium, Colocasia (i.e., taro), and Alocasia.

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The leaves of most Xanthosoma species are 40-200 cm long, saggitate (arrowhead-shaped) or subdivided into 3 or as many as 18 segments. Unlike the leaves of Colocasia, those of Xanthosoma are usually not peltate—the upper v-notch extends in to the point of attachment of the leaf petiole to the blade.

Pollination biology

Inflorescences of Xanthosoma are composed by a spadix with pistillate flowers at the base, a belt of sterile flowers offered as a reward for pollinators in the middle, and staminate flowers on the upper part. Prior to opening, the inflorescence is enclosed within a leaf-like spathe. When the inflorescence is ready to open, the upper part of the spathe opens and exposes the staminate area of the spadix; the basal area of the spathe remains closed, forming a spacious chamber (i.e., the spathe tube) that encloses the pistillate and sterile flowers (García-Robledo et al. 2004; 2005a; 2005b).

The inflorescences last for two nights and are protogynous (but see Valerio 1988), changing from the pistillate phase that attracts pollinators on the night it opens, to a staminate phase on the second night, when pollen is shed (Garcıa-Robledo et al. 2004; 2005a; 2005b). When inflorescences open, produce heat and release a sweet scent attracting its pollinators, Dynastine beetles (Cyclocephala spp.). Dinastines arrive covered with pollen from another inflorescence, and remain in the spathe tube for 24 h, pollinating the pistillate flowers as they feed on the sterile area of the spadix. On the second night, they come out of the tube and walk over the staminate flowers, getting covered with pollen and then flying to the nearest recently opened inflorescence (García-Robledo et al. 2004; 2005a; 2005b).

Fruit maturation takes several months. Fruits start to grow within the shelter of the spathe tube. When the infructescence is mature, in some species it arches back and downwards. In other species it stays erect. Then, the tissue of the spathe tube rolled outwards, exhibiting the bright orange fruits and the velvety pink inner spathe surface (García-Robledo et al. 2004; 2005a; 2005b).

Crop uses

Domestication of Xanthosoma species (especially X. saggitifolium but also X. atrovirens, X. violaceum, X. maffaffa, and others) is thought to have originated in northern lowland South America then spread to the Antilles and Mesoamerica. Today Xanthosoma is still grown in all those regions but is especially popular in Cuba and Puerto Rico, where it is used in Alcapurrias. It is grown in Trinidad and Tobago, Guyana and Jamaica to make the popular callaloo dish.It is also grown in West Africa, now a major producer, where it can be used as a replacement for yams in a popular regional dish called fufu. Xanthosoma is also grown as a crop in the Philippines.

Traditionally Xanthosoma has been a subsistence crop with excess sold at local markets, but in the United States, large numbers of Latin American immigrants have created a market for commercial production. In general, production has yet to meet demand in some areas. In Polynesia, Xanthosoma (‘ape) was considered a famine food, utilized only in the event of failure of the much preferred taro (kalo) crop.

The typical Xanthosoma plant has a growing cycle of 9 to 11 months, during which time it produces a large stem called a corm, this surrounded by smaller edible cormels about the size of potatoes. These cormels (like the corm) are rich in starch. Their taste has been described as earthy and nutty and they are a common ingredient in soups and stews. They may also be eaten grilled, fried, or puréed. The young, unfurled leaves of some varieties can be eaten as boiled leafy vegetables or used in soups and stews, such as the Caribbean callaloo.

Xanthosoma starch is highly hypoallergenic due to the small size of the starch grains.

References

García -Robledo, C., G. Kattan, C. Murcia, P. Quintero.2005a. Equal and opposite effects of floral offer and spatial distribution on fruit production and pre-dispersal seed predation in Xanthosoma daguense (Araceae). Biotropica. 37: 373-380

García–Robledo, C., P. Quintero-Marín. F. Mora-Kepfer. 2005b. Geographic Variation and Succession of Arthropod Communities in Inflorescences and Infructescences of Xanthosoma (Araceae). Biotropica. 37: 650-656

García-Robledo, C. , G. Kattan, C. Murcia and P. Quintero. 2004. Beetle pollination and fruit predation in Xanthosoma daguense (Araceae). Journal of Tropical Ecology. 20: 459 – 469

Valerio, C. E. 1988. Notes on the phenology and pollination of Xanthosoma wendlandii (Araceae) in Costa Rica. Revista de Biologıa Tropical 36:55–61.