Lupinus argenteus Pursh

 

by Angelina Robinson, Native Plants of Arizona 2007
Common names:
Silvery lupine (1, 2, 3, 5, 8), silver stem lupine (2), wolfbean (9).
Family: Fabaceae (1, 4, 8) (alt. Leguminosae) (2)
Synonymy: Lupinus laxiflorus var. foliosus, Lupinus sitgreavesii, Lupinus garrettianus, Lupinus decumbens, Lupinus laxiflorus var. corymbosus, Lupinus argenteus var. decumbens, Lupinus foliosus (9).
Etymology: Lupinus refers to “of the wolf” or lupine “wolf-like” and is thought to be named after a belief that the plants were harmful to soil (2, 7); argenteus or argentum means “silvery” and refers to the hairs on the stems and leaves (7).  

Identification
Growth form:
Subshrub or herbaceous perennial (1, 2, 8, 9).
Roots: Has root nodules containing bacteria that aid in nitrogen deposition (2).
Stem: One to several, erect or ascending , 30-80 cm. (12-30 in.) tall (8), covered with silvery hairs (2, 8)
Leaves:  Alternate, palmately compound (8, 9), 5 to 10 nearly linear oblanceolate leaflets 2-8 cm. long (8), dark green glabrous above, light green with dense hairs below (2),
Inflorescence/flowers: Many flowered terminal raceme 5 to 25 cm. long (8). Flowers violet, lilac, rarely white (9), banner petal wide with hairs on back (2), wing petals 8 to 12 mm., keel deep and swollen, corolla blue, calyx bent away from keel almost perpendicular to pedicel (8).
Fruit: Hairy obovate pods, 20 to 35 mm. long, 6 to 9 mm. wide (8).
Similar species: There are 23 species in the genera Lupinus. Lupinus argenteus can be identified from other species of Lupinus by its elevation, leaf shape, and silvery-haired stem (2). 

Ecology
Life history:
Perennial herb orsubshrub (1).
Native/introduced: Native (1).
Photosynthetic pathway:
Phenology:  Flowers June to October (2).
Distribution: 7,000 to 10,000 (2135 to 3050 m) feet elevation (2, 5, 8). Found in clearing of coniferous forests of Apache, Coconino, and Mohave, and Navajo Countys in Arizona (8).  Western United States (1).  

Uses
Seed are eaten by many bird species (2). Used as a dermatological aid (4). Navajo make a poultice out of the dried leaves and apply poison ivy blisters (4, 8). The root nodules of legume species are known to positively affect soil nitrogen content by absorbing free nitrogen from the air and enriching the soil through their roots (3, 8). Lupinus argenteus as well as many other forbs have been integrated into land restoration seed mixes in order to improve degraded soil (3). Several species of lupine including L. argenteus are poisonous to livestock, causing “crooked calf disease” in cattle and death in sheep (6).

References

1.  USDA, NRCS. 2007. The PLANTS Database (http://plants.usda.gov, 12 November 2004). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

2.  Epple, A. O.  1995.  A Field Guide to the Plants of Arizona.  Falcon Publishing.  Helena, Montana. 

3.  USDA, NRCS. 2004. The PLANTS Database, Version 3.5, Symbiotic Nitrogen Fixation and Establishment of Six Montana Native Legume Species (http://www.mt.nrcs.usda.gov/technical/ecs/plants/technotes/pmtechnoteMT54.html). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

4.  Moerman, D. 2003. Native American Ethnobotany Database (http://herb.umd.umich.edu/). University of Michigan, Dearborn, MI 48198 USA.

5. Dittmann, L. 007. NAZ Flora A photographic, Annotated catalog of Northern Arizona vascular plants (http://www.nazflora.org/Fabaceae.htm). Mindbird Maps & Books, Cottonwood, AZ 86326.

6. Lopez-Ortiz, S. 2004. The effect of body condition on disposition of alkaloids from silvery lupine (Lupinus argenteus Pursh) in sheep. Journal of Animal Science, Vol. 82:2798-2805.

7. Harper, D. 2001. Online Etymology Dictionary (http://www.etymonline.com/index.php). 

8. Springer, J. et al. 2003. Plants of Northern Arizona Forests Draft. Ecological Restoration Institute, Northern Arizona University, Flagstaff, Arizona.

9. Faucon, P. 2007. Desert Tropicals. (http://www.desert-tropicals.com/Plants/Fabaceae/Lupinus_argenteus.html ).