Yardlong bean
Vigna unguiculata subsp. sesquipedalis (L.) Verdc.
The yardlong bean (Vigna unguiculata subsp. sesquipedalis) is a climbing legume grown for its edible pods 35–75 cm long; widely cultivated in Southeast Asia and southern China, rich in protein, vitamin A, C and folate.
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Gallery
Yardlong bean — vines (Hong Kong)Yardlong bean — harvesting the long pods
Yardlong bean — long pods
Yardlong bean — flower
Yardlong bean — flower (close-up)
Yardlong bean — plantYardlong bean — vines (Hong Kong)Yardlong bean — harvesting the long podsOverview
The asparagus bean or yardlong bean (Vigna unguiculata subsp. sesquipedalis) is an annual climbing (sometimes semi-bush) legume in the family Fabaceae, genus Vigna, a subspecies of the cowpea Vigna unguiculata (the same species as the black-eyed pea). The twining stem can reach 2–3 m on supports; the leaves are alternate and trifoliolate with ovate to triangular leaflets and entire margins. Flowers are borne in the leaf axils or at the tip in clusters of 2–5 pairs, pale yellow or purple and bilaterally symmetrical, pollinated by insects such as wasps and bees. The fruit is an exceptionally long pod — 35 cm to 75 cm (the epithet sesquipedalis means “one-and-a-half feet long”) — usually produced in pairs and containing many kidney-shaped seeds that vary from white to red, brown or black. Pods are harvested about 60 days after sowing.
Updated by lebachungtdh@gmail.com · 10/12/2026
The parent species Vigna unguiculata originated in Africa, while the subspecies sesquipedalis was domesticated and is widely grown in Southeast Asia and southern China; today the yardlong bean is cultivated throughout the tropics and subtropics, including the Americas and Oceania. It is an important traditional food crop in Asia and Africa that contributes to food security. The young pods are a familiar vegetable: in Vietnam they are usually cut into short lengths and boiled or stir-fried with beef or dried shrimp; in the West Indies they are sautéed with potato and prawns; in Malaysia stir-fried with chilli and shrimp paste; they can also be fried with egg. Nutritionally, the pods are rich in protein, vitamin A (beta-carotene), vitamin C, folate, thiamin, riboflavin and the minerals iron, magnesium, manganese, phosphorus and potassium; 100 g of seeds supplies about 47 kcal. As a legume, the plant also fixes nitrogen, improves the soil and provides fodder from stems and leaves. Note that pods and seeds must be cooked, because they contain lectins and trypsin inhibitors that cause indigestion when eaten raw.
Updated by lebachungtdh@gmail.com · 10/12/2026
Life cycle
From seed to productPlant
Annual climbing vine twining up supports with tendrils; leaves are trifoliolate.
Flowers
Pale yellow or purple flowers in axillary clusters, pollinated by bees and insects.
Young pods
Young pods 35–75 cm long, usually borne in pairs; this is the part eaten as a vegetable.
Harvest
Young pods are harvested about 60 days after sowing; frequent picking keeps the plant producing.
Distribution & origin
Share of recorded occurrences by region- Southeast Asia (main growing centre)25%
- Southern China & East Asia20%
- South Asia (India)20%
- Africa (parent species and cultivation)20%
- Americas & Oceania (introduced)15%
Chemical composition
Relative content in agarwood resin- Protein & amino acidsRich plant protein in pods and seeds25%
- Dietary fibreSupports digestion15%
- Vitamins (C, A/beta-carotene, B1, B2, folate)Antioxidant, immune support25%
- Minerals (Fe, Mg, Mn, P, K, Ca)15%
- Flavonoids & anthocyaninsHigher in red/black-seeded varieties10%
- Lectins, saponins & trypsin inhibitorsAntinutrients — must be cooked10%
Uses
- Food: the young pods are a common vegetable — in Vietnam cut short and boiled or stir-fried with beef or dried shrimp; in the West Indies sautéed with potato and prawns; in Malaysia stir-fried with chilli and shrimp paste; also fried with egg.
- Seeds and processed products: the protein-rich seeds are eaten immature or dried for soups, pickles and other foods.
- Agriculture: a nitrogen-fixing legume that improves soil; often intercropped or rotated with rice and vegetables, reducing nitrogen fertiliser needs.
- Fodder & food security: stems and leaves are used as fodder; it is an important traditional food crop in Asia and Africa contributing to food security.
- Safety note: pods and seeds should be well cooked to destroy lectins and trypsin inhibitors; eating them raw or undercooked may cause bloating and indigestion.
Properties
- Form
- Annual vine with trifoliolate leaves, yellow/purple flowers and very long pods
- Hallmark
- Young pods 35–75 cm, borne in pairs; harvested ~60 days after sowing
- Products
- Green-pod vegetable (stir-fry, boil, salad), dried seeds, fodder, green manure
- Safety
- Must be cooked (lectins/trypsin inhibitors); raw seeds cause indigestion
Habitat & conservation
The yardlong bean prefers hot, humid tropical and subtropical climates, growing best at 20–30 °C with plenty of sun; it is usually grown on supports for the climbing stems, on a range of well-drained soils from loams to riverside alluvium. It tolerates heat better than many other bean varieties, so it suits hot, humid summers. The parent species is native to Africa, and the subspecies is widely cultivated in Southeast Asia and southern China.
Conservation
The yardlong bean is a widespread cultivated crop that is not threatened; the subspecies has not been assessed by the IUCN and is therefore listed as Not Evaluated (NE). Family Fabaceae, genus Vigna, species Vigna unguiculata. Values: food vegetable, nitrogen fixation and soil improvement, fodder.
References
- 1Plants of the World Online — Vigna unguiculata subsp. sesquipedalis (L.) Verdc. — Kew Science, 2026
- 2GBIF Backbone Taxonomy — Vigna unguiculata subsp. sesquipedalis (L.) Verdc. — GBIF, 2026
- 3Asparagus bean (yardlong bean) — description, cultivation, uses and nutrition — English Wikipedia, 2026
- 4Đậu đũa — đặc điểm, giống cây trồng, sử dụng và dinh dưỡng — Vietnamese Wikipedia, 2026
- 5長豇豆 — 形態、營養成分與用途 — Chinese Wikipedia, 2026
- 6Nguồn ảnh: Vis M, M Joko Apriyo Putro, Yercaud-elango (CC BY-SA 4.0) — Wikimedia Commons,
- 7Nguồn ảnh: Reji Jacob & Aruna (CC BY-SA 3.0); 阿橋 HQ (CC BY-SA 2.0) — Wikimedia Commons,