Lupin, often spelled lupine in North America, is the common name for members of the [[genus Lupinus in the legume family (Fabaceae). The genus comprises between 200-600 species, with major centers of diversity in South America and western North America - subgen.Platycarpos) and subgen. Lupinus - in the Mediterranean region and Africa.

Like most members of their family, lupins can fix nitrogen from the atmosphere into ammonia, fertilizing the soil for other plants. The genus Lupinus is nodulated by Bradyrhizobium soil bacteria. Some species have a long central tap roots, or have proteoid roots.

Lupins contain significant amounts of certain secondary compounds like isoflavones and toxic alkaloids, e.g. lupinine and sparteine.

Cultivation and uses

The yellow legume seeds of lupins, commonly called lupin beans, were popular with the Romans, who spread the plant's cultivation throughout the Roman Empire; hence common names like lupini in Romance languages. Lupin beans are commonly sold in a salty solution in jars (like olives and pickles) and can be eaten with or without the skin. Lupins are also cultivated as forage and grain legumes.

thumb|left|Blue Lupin, L. angustifolius Lupini dishes are most commonly found in Mediterranean countries, especially in Portugal, Egypt, and Italy, and also in Brazil and in Spanish Harlem, where they are popularly consumed with beer. The Andean variety of this bean is from the Andean Lupin (tarwi, L. mutabilis) and was a widespread food in the Incan Empire. The Andean Lupin and the Mediterranean L. albus (White Lupin), L. angustifolius (Blue Lupin) and Lupinus hirsutus are also edible after soaking the seeds for some days in salted water. They are known as altramuz in Spain and Argentina. In Portuguese the lupin beans are known as tremoços, and in Antalya (Turkey) as tirmis . Lupins were also used by Native Americans in North America, e.g. the Yavapai people. These lupins are referred to as sweet lupins because they contain smaller amounts of toxic alkaloids than the bitter lupin varieties. Newly bred variants of sweet lupins are grown extensively in Germany; they lack any bitter taste and require no soaking in salt solution. The seeds are used for different foods from vegan sausages to lupin-tofu or baking-enhancing lupin flour. Given that lupin seeds have the full range of essential amino acids and that they, contrary to soy, can be grown in more temperate to cool climates, lupins are becoming increasingly recognized as a cash crop alternative to soy.