Bigleaf Lupine

Appearance

It is a perennial herbaceous plant with stout stems growing to 1.5 metres tall. The leaves are palmately compound with 9-17 leaflets 3–15 centimetres long. The flowers are produced on a tall spike, each flower 1–1.5 centimetres long, most commonly blue to purple in wild plants. The polyphyllus variety in particular make up a great number of the hybrids which are generally grown as garden lupins, they can vary dramatically in colours. The majority of lupins do not thrive in rich heavy soils, and often only live for a matter of years if grown in such places, crown contact with manure or rich organic matter encourages rotting.

Naming

There are five varieties:
⤷ "Lupinus polyphyllus" var. "burkei" – Interior northwestern United States
⤷ "Lupinus polyphyllus" var. "humicola" – Interior western North America
⤷ "Lupinus polyphyllus" var. "pallidipes" – Western Oregon and Washington
⤷ "Lupinus polyphyllus" var. "polyphyllus" – Coastal western North America
⤷ "Lupinus polyphyllus" var. "prunophilus" – Interior western North America

Status

In New Zealand, where it is known as the Russell lupin, "Lupinus polyphyllus" is classed as an invasive species and covers large areas next to roadsides, pastures and riverbeds, especially in the Canterbury region. It is documented as being first naturalised in 1958 and it has been suggested that tour bus drivers deliberately spread seeds of the plant to promote colourful roadside vegetation in areas which some tourists may consider to be rather drab.

The plant threatens indigenous species especially when it invades the braided river beds in the South Island.

It is also classed as an invasive species in Switzerland, Czech Republic and Finland.

Uses

It is commonly used in gardens for its attractiveness to bees, ability to improve poor sandy soils with their nitrogen fixing ability and flowers; numerous cultivars have been selected for differing flower colour, including red, pink, white, blue, and multicoloured with different colours on different petals. Often hybrids between "L. polyphyllus" and "L. arboreus" are used, and sold under hybrid names such as Rainbow Lupins, Lupin Tutti Fruitti, and Band of Nobles, Chandelier, My Castle, Noble Maiden The Chatelaine, and The Governor. They are very hardy plants, surviving extreme temperatures withstanding frost to at least −25 °C and the wild varieties can easily become invasive and hard to dispose of unless kept in check on a regular basis. They need a reasonable level of sun to survive, and do best in light soils, suffering in heavy and clay types, once fully established they are extremely resilient and may be divided. Seeds taken from the mother plant will never be a true replica of the original even if they produce similar colourings.

Low alkaloidal or sweet cultivars of this lupin suitable for fodder crops have been bred. To avoid restoration of alkaloid synthesis in cross-pollinated species of lupin, a new approach has been developed on the basis of specific crossing. Only compatible forms are involved in hybridization, with their low alkaloid content controlled by one and the same genetic system. These approaches have allowed transforming this bitter weed into a valuable fodder crop. In the conditions of Northwest Russia positive results from the use of the sweet commercial cultivar 'Pervenec', which is included in the State Catalogue of selection achievements of Russia. Breeding of sweet lupin is carried out also in Finland. The newer garden hybrids of today are highly poisonous because they are full of toxic alkaloids and should never be eaten.