Lupinus argenteus
In Iron County, Utah
Conservation status
Secure  (NatureServe)[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Fabales
Family:	Fabaceae
Subfamily:	Faboideae
Genus:	Lupinus
Species:	L. argenteus
Binomial name
Lupinus argenteus Pursh
Subspecies and varieties[2]
List L. a. subsp. argenteus L. a. var. fulvomaculatus L. a. var. laxiflorus L. a. var. moabensis L. a. var. myrianthus L. a. var. palmeri L. a. var. parviflorus L. a. var. rubricaulis L. a. subsp. spathulatus

Lupinus argenteus is a species of lupine known by the common name silvery lupine. It is native to much of western North America from the southwestern Canadian provinces to northernmost Mexico and as far east as the Great Plains. It grows in several types of habitats, including sagebrush, grassland, and forests.

Lupinus argenteus is a perennial plant with one or more stems that that usually grow 15 to 70 centimeters (0.5 to 2.3 ft) tall, but occasionally can be as short as 10 cm (4 in) or as tall as 1.2 m (3 ft 11 in). The stems branch towards their ends or have short spurs and are green or somewhat purple in color.^[3] They are covered with hairs that can be puberulent, fine short and erect, or strigose, straight and all pointing in the same direction.^[4] The stems grow from a root-crown at the surface of the soil or shallowly burried.^[3]

The leaves can appear green, ashy, or canescent, nearly white in color, due to either being hairless or covered in hairs on their upper surface.^[3] Most of the leaves are cauline, attached to the stems of the plants. Each leaf is palmate, made up of leaflets radiating from a central attachment point, with six to nine leaflets for this species and attached by a petiole 1.5–8 cm long.^[5]

The flowers are in racemes that can be 4 to 30 centimeters (1.6 to 11.8 in) long, but more usually 5 to 25 cm (2 to 10 in). They are either solitary at the end of stem or one larger one at the end of the stem with smaller racemes branching off below the primary, or several nearly equal in size.^[6] The flowers are typically blue-purple, but occasionally are lavender, pink, or white, but with a white or yellow spot on the uppermost banner petal that turns red-purple as the flower ages.^[7]

The fruit is a pod that is densely hairy containing two to six seeds and measuring 2–3 cm by 0.6–0.9 cm.^[6]

Lupinus argenteus was scientifically described by Frederick Traugott Pursh in 1813. It is part of the genus Lupinus in the family Fabaceae.^[2] He described it using specimens collected by Meriwether Lewis in an area he described as, "On the banks of the Kooskoosky River". This is now named the Clearwater River which forms the present day western Montana boarder with Idaho.^[8]

There are two accepted subspecies and seven accepted botanical varieties of Lupinus argenteus.^[2][9] Each of these infraspecifics has one or more accepted synonyms.^{[10][11][12][13][14][15][16][17][18]}

• Lupinus argenteus subsp. argenteus
• Lupinus argenteus var. fulvomaculatus (Payson) Barneby
• Lupinus argenteus var. laxiflorus (Douglas ex Lindl.) Dorn
• Lupinus argenteus var. moabensis S.L.Welsh
• Lupinus argenteus var. myrianthus (Greene) Isely
• Lupinus argenteus var. palmeri (S.Watson) Barneby
• Lupinus argenteus var. parviflorus (Nutt. ex Hook. & Arn.) C.L.Hitchc.
• Lupinus argenteus var. rubricaulis (Greene) S.L.Welsh
• Lupinus argenteus subsp. spathulatus (Rydb.) L.W.Hess & D.B.Dunn

The species name, argenteus, means silvery and its common name is silvery lupine.^[4]

Silver lupins grow throughout the western United States, parts of western Canada, and two states in Mexico.^[19] In Canada it grows in the provinces of British Columbia, Alberta, and Saskatchewan. In the Pacific Northwest it is native to the eastern portions of Washington and Oregon as well as almost all of Idaho. To the east the species grows throughout the Rocky Mountains in the states of Montana and Wyoming and onto the Northern Great Plains as far as western North Dakota and South Dakota. South of this they are mostly found in the Nebraska panhandle and all but the most eastern portions of Colorado.^[20] It may also be native to Kansas, but there is not specific location to the records and it is not listed in the Flora of the Great Plains as occurring in Kansas.^[20][21] In Mexico it grows in the northwest in Chihuahua and Sonora.^[19]

It grows in a wide range of plant communities including with ephedra, in grasslands, sagebrush steppes, piñon–juniper woodlands, ponderosa pine forests, aspen groves, and even with spruce-fir communities.^[22]

Many butterflies use silvery lupins as a food plant while catepilliars including the arrowhead blue (Glaucopsyche piasus),^[23] gray hairstreak (Strymon melinus),^[24] lupine blue (Icaricia icarioides),^[25] and silvery blue (Glaucopsyche lygdamus).^[26] It is an alternate food plant for the catepillers of the hops azure butterfly (Celastrina humulus).^[27]

Books

Web sources

Wikimedia Commons has media related to Lupinus argenteus.

• Jepson eFlora Treatment