Flower The species are mostly herbaceous perennial plants 0.3–1.5 metres (1–5 feet) tall, but some are annual plants and a few are shrubs up to 3 m (10 ft) tall. An exception is the chamis de monte (Lupinus jaimehintonianus) of Oaxaca in Mexico, which is a tree up to 8 m (26 ft) tall.[3] Lupins have soft green to grey-green leaves which may be coated in silvery hairs, often densely so. The leaf blades are usually palmately divided into five to 28 leaflets, or reduced to a single leaflet in a few species of the southeastern United States and eastern South America.[4] The flowers are produced in dense or open whorls on an erect spike, each flower 1–2 centimetres (3⁄8–3⁄4 inch) long. The pea-like flowers have an upper standard, or banner, two lateral wings, and two lower petals fused into a keel. The flower shape has inspired common names such as bluebonnets and quaker bonnets. The fruit is a pod containing several seeds. The seeds contain alkaloids which lend them a bitter taste. The legume seeds of lupins, commonly called lupin beans, were popular with the Romans, who cultivated the plants throughout the Roman Empire where the lupin is still known in extant Romance languages by names such as lupini. Seeds of various species of lupins have been used as a food for over 3,000 years around the Mediterranean[61] and for as long as 6,000 years in the Andes.[62] Lupins were also used by many Native American peoples of North America such as the Yavapai. The Andean lupin or tarwi (Lupinus mutabilis) was a widespread food in the Incan Empire; but they have never been accorded the same status as soybeans, dry peas and other pulse crops. The pearl lupin of the Andean highlands of South America, L. mutabilis, known locally as tarwi or chocho, was extensively cultivated, but no conscious genetic improvement other than to select for larger and water-permeable seeds seems to have been made. Users soaked the seed in running water to remove most of the bitter alkaloids and then cooked or toasted the seeds to make them edible,[63][full citation needed] or else boiled and dried them to make kirku,[62] reported as a pre-Columbian practice in Las Relaciones geográficas de Indias.[64] Spanish domination led to a change in the eating habits of the indigenous peoples, and only recently[65] (late 20th century onward) has interest in using lupins as a food been renewed.