Buckwheat (fagopyrum esculentum), or common buckwheat, is a plant cultivated for its grain-like seeds and as a cover crop. the name "buckwheat" is used for several other species, such as fagopyrum tataricum, a domesticated food plant raised in asia. despite its name, buckwheat is not closely related to wheat. it is not a cereal, nor is it even a member of the grass family. buckwheat is related to sorrel, knotweed, and rhubarb, and is known as a pseudocereal because its seeds' culinary use is the same as cereals, owing to their composition of complex carbohydrates.

Source: Wikipedia