Buckwheat (Fagopyrum esculentum), or common buckwheat, is a plant cultivated for its grain-like seeds and as a cover crop. The name "buckwheat" is also used for a number of other species. A related and bitterer species, Fagopyrum tataricum, is a domesticated food plant raised in Asia. Despite the name, buckwheat is not related to wheat, as it is not a grass. Instead, buckwheat is related to sorrel, knotweed, and rhubarb. Buckwheat is referred to as a pseudocereal because its seeds' culinary use is the same as cereals', owing to their composition of complex carbohydrates.
Common buckwheat was domesticated and first cultivated in inland Southeast Asia, possibly around 6000 BCE, and from there spread to Central Asia and Tibet, and then to the Middle East and Europe. Domestication most likely took place in the western Yunnan region of China.
Buckwheat, a short-season crop, does well on low-fertility or acidic soils, but the soil must be well drained. Too much fertilizer, especially nitrogen, reduces yields. In hot climates it can be grown only by sowing late in the season, so that it blooms in cooler weather. The presence of pollinators greatly increases the yield. The nectar from buckwheat flower makes a dark-colored honey. Buckwheat is sometimes used as a green manure, as a plant for erosion control, or as wildlife cover and feed.
With a 100-gram serving of dry buckwheat providing 1,440 kilojoules (343 kilocalories) of food energy, or 380 kJ (92 kcal) cooked, buckwheat is a rich source (20% or more of the Daily Value, DV) of protein, dietary fiber, four B vitamins and several dietary minerals, with content especially high (47 to 65% DV) in niacin, magnesium, manganese and phosphorus (table). Buckwheat is 72% carbohydrates, including 10% dietary fiber, 3% fat and 13% protein.
Buckwheat contains fluorescent phototoxic fagopyrins. Seeds, flour, and teas are generally safe when consumed in normal amounts, but fagopyrism can appear in people with diets based on high consumption of buckwheat sprouts, and particularly flowers or fagopyrin-rich buckwheat extracts. Symptoms of fagopyrism in humans may include skin inflammation in sunlight-exposed areas, cold sensitivity, and tingling or numbness in the hands.
Buckwheat noodles have been eaten in Tibet and northern China for centuries, where the growing season is too short to raise wheat. A wooden press is used to press the dough into hot boiling water when making buckwheat noodles. Old presses found in Tibet and Shanxi share the same basic design features. The Japanese and Koreans may have learned the making of buckwheat noodles from them.
Buckwheat groats are commonly used in western Asia and eastern Europe. The porridge was common, and is often considered the definitive peasant dish. It is made from roasted groats that are cooked with broth to a texture similar to rice or bulgur. The dish was taken to America by Ukrainian, Russian, and Polish immigrants who called it kasha, and they mixed it with pasta or used it as a filling for cabbage rolls (stuffed cabbage), knishes, and blintzes; buckwheat prepared in this fashion is thus most commonly called kasha in America. Groats were the most widely used form of buckwheat worldwide during the 20th century, eaten primarily in Estonia, Latvia, Russia, Ukraine, Belarus, and Poland, called grechka in Ukrainian or Russian.
Buckwheat is a permitted sustenance during fasting in several traditions. In India, on Hindu fasting days (Navaratri, Ekadashi, Janmashtami, Maha Shivaratri, etc.), fasting people in northern states of India eat foods made of buckwheat flour. Eating cereals such as wheat or rice is prohibited during such fasting days. While strict Hindus do not even drink water during their fast, others give up cereals and salt and instead eat non-cereal foods such as buckwheat (kuttu). In the Russian Orthodox tradition, it is eaten on the St. Philip fast.
Buckwheat hulls are used as filling for a variety of upholstered goods, including pillows and zafu. The hulls are durable and do not insulate or reflect heat as much as synthetic filling. They are sometimes marketed as an alternative natural filling to feathers for those with allergies. However, medical studies to measure the health effects of pillows manufactured with unprocessed and uncleaned hulls concluded that such buckwheat pillows do contain higher levels of a potential allergen that may trigger asthma in susceptible individuals than do new synthetic-filled pillows.