Description
Water yam, scientifically known as Dioscorea alata, is a species of yam that is widely cultivated in tropical and subtropical regions. It is known for its high moisture content and large, starchy tubers. Here’s a detailed description:
General Characteristics
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Scientific Name: Dioscorea alata
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Common Names: Water yam, winged yam, purple yam (in some regions), greater yam
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Origin: Thought to be native to Southeast Asia or Melanesia, now widely grown in Africa, the Caribbean, and parts of Asia and the Pacific.
Physical Description
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Tuber Appearance: Large, cylindrical or club-shaped tubers with rough, brown to grayish skin. The flesh is usually white but can also be purple, depending on the variety.
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Leaves: Heart-shaped or oval with a glossy green surface.
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Vines: Long, twining vines that can grow up to several meters, supported by aerial stems with wing-like ridges (hence the name “winged yam”).
Culinary Use
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Water yam is typically boiled, pounded, fried, or used to make porridge, fufu, or yam flour.
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It is softer and more watery when cooked compared to other yam varieties, like white yam (Dioscorea rotundata).
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In some cultures, it is used to make yam dough (like amala in Nigeria) or yam cakes.
Nutritional Value
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High in carbohydrates (mainly starch)
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Contains dietary fiber, vitamin C, potassium, and some B vitamins
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Lower in protein and fat
Agronomic Features
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Growing Season: Usually grown during the rainy season
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Propagation: By tuber pieces or whole tubers
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Soil Requirement: Prefers well-drained, fertile soils
Health and Functional Benefits
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Provides a good source of energy
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The purple-fleshed varieties are rich in antioxidants, particularly anthocyanins
Note on Terminology
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Water yam is sometimes confused with other root crops like ube (purple yam), but these are botanically different despite some visual and culinary similarities.
