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.
The species are mostly herbaceous perennial plants 0.3-1.5 m (1-5 ft) tall, but some are annual plants and a few are shrubs up to 3 m (10 ft) tall - see also bush lupin -, with one species (Lupinus jaimehintoniana, from the Mexican state of Oaxaca) a tree up to 8 m high with a trunk 20 cm (8 in) in diameter. They have a characteristic and easily recognised leaf shape, with soft green to grey-green leaves which in many species bear silvery hairs, often densely so. The leaf blades are usually palmately divided into 5–28 leaflets or reduced to a single leaflet in a few species of the southeastern United States. The flowers are produced in dense or open whorls on an erect spike, each flower 1-2 cm long, with a typical peaflower shape with an upper 'standard', two lateral 'wings' and two lower petals fused as a 'keel'. Due to the flower shape, several species are known as bluebonnets or quaker bonnets. The fruit is a pod containing several seeds.
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.
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.
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.
Three Mediterranean species of lupin, Blue Lupin, White Lupin and Yellow Lupin (L. luteus) are widely cultivated for livestock and poultry feed. Both sweet and bitter lupins in feed can cause livestock poisoning. Lupin poisoning is a nervous syndrome caused by alkaloids in bitter lupins, similar to neurolathyrism. Mycotoxic lupinosis is a disease caused by lupin material that is infected with the fungus Diaporthe toxica; the fungus produces mycotoxins called phomopsins, which cause liver damage.
On 22 December 2006, the European Commission submitted directive 2006/142/EC, which amends the EU foodstuff allergen list to include "lupin and products thereof".
Lupins are popular ornamental plants in gardens. There are numerous hybrids and cultivars. Some species, such as Garden Lupin (Lupinus polyphyllus) and hybrids like the Rainbow Lupin (L. × regalis) are common garden flowers. Others, such as the Yellow Bush Lupin (L. arboreus) are considered invasive weeds when they appear outside their native range.
In New Zealand lupins have escaped into the wild and grow in large numbers along main roads and streams on the South Island. The seeds are carried by car tires and water flow, and unfortunately, some tourist shops in the major tourist areas have been reported to have sold packets of lupin seeds, with the instructions to plant, water and watch them grow into a giant beanstalk. They are usually Garden Lupins, principally blue, pink and violet, with some yellow, and are very attractive, providing colourful vistas with a backdrop of mountains and lakes; however, they smother the original vegetation. The New Zealand environment authorities have a campaign to reduce their numbers, although this seems a hopeless task, especially when faced with such ignorance as mentioned above. In fields they seem to be eradicated by sheep, and hence remain largely restricted to ungrazed roadside verges and stream banks.
There are two subgenera of the genus Lupinus L.: Subgen. Platycarpos and Subgen.