Fagopyrum esculentum aka Buckwheat

Fagopyrum esculentum, or buckwheat, belongs to the knotweed family. It is an annual: it lives for one year. Its native range spans eastern Tibet, Sichuan, and Yunnan. Farmers now grow it in many regions with temperate climates. It also grows in subtropical lands and tropical highlands. Plants sometimes escape fields and grow on waste ground. Buckwheat provides food, feed for animals, and cover for bare soil. Farmers use it as green manure, but it is not a legume.

Plants grow upright, with branches and hollow stems. Most reach about 2–4 feet [0.6–1.2 metres] tall. One source gives a taller height of 5 feet [1.5 metres]. Stems start pale green, then gain ribs and red tones. Plants may sprawl and need support as they grow. Green leaves grow in turn along the stems. Leaves have smooth edges and heart or arrowhead shapes. Lower leaves have stalks; upper leaves join the stems without stalks. Swollen sheaths sit where leaves meet the stem.

Small, scented flowers grow in dense clusters called racemes. These form near the upper leaves. Flowers bloom in summer and fall, sometimes for three months. Five white sepals look like petals, but flowers lack true petals. Some flowers have a pink tint on the outside. Bees and flies pollinate the flowers. Plants cannot set seed with their own pollen. After bloom, plants form brown, three-sided fruits called achenes. Harvest takes place in fall. Birds and mammals eat some of the seed. Flowers give nectar to bees and other useful insects. Cut stems keep their flowers well in bouquets.

Buckwheat grows fast; seeds can sprout within four days. It grows in full sun or some shade. It suits moist soil that drains well. It accepts sand, loam, clay, and soils low in nutrients. Too much nitrogen can reduce the crop's yield. It grows in acid, neutral, and alkaline soils. Frost can harm it with ease. Its one-year life matters more than its winter survival. Dense growth shades out weeds, but plants can spread by seed. NCSU lists no known diseases or insect pests.

Cooked seeds with their husks removed serve as grain. They can also make flour. Sources list edible leaves, eaten raw or cooked. Yet the plant poses key food and skin risks. Buckwheat can cause food allergies. It can also cause skin reactions after sun exposure. Contact can cause dermatitis, a form of skin rash. Sheep, pigs, and cattle face similar sun-linked skin problems. Sources regard only grain with its husks removed as safe. Even this grain carries allergy risks. Other uses include soil repair and dyes. Traditional medicine uses the leaves, which are rich in rutin.