About Lupinus sericeus Pursh
Lupinus sericeus Pursh, a flowering plant species in the legume family, is commonly known as silky lupine or Pursh's silky lupine. It is native to western North America, ranging from British Columbia south to Arizona, and east to Alberta and Colorado. This is a perennial herb that grows erect stems from a woody caudex connected to a deep root system. Stems can reach up to 50 centimeters (20 inches) tall, and they may or may not branch. The stems are covered in silvery or reddish hairs. Each leaf holds up to 9 lance-shaped leaflets, with each leaflet reaching up to 6 centimeters (2.4 inches) long. The leaflets are coated in fine, silk-like hairs. The inflorescence is a raceme holding many flowers, which are most often purple or blue, but can occasionally be white or yellowish. The back of the banner petal is covered in hairs. The fruit is a hairy legume pod up to 3 centimeters (1.2 inches) long, and holds up to 7 seeds. This plant grows in a wide variety of habitat types, including forests, woodlands, chaparral, shrubsteppe, sagebrush, and grasslands. It often occurs on dry, rocky slopes, and grows best in open, unshaded sites. It can be found at both low and high elevations, growing up to 3,000 meters (9,800 feet) or higher, and it frequently colonizes recently burned sites. Plant species commonly associated with Lupinus sericeus include Gambel oak (Quercus gambelii), common snowberry (Symphoricarpos albus), ninebark (Physocarpus malvaceus), serviceberry (Amelanchier spp.), mountain-mahogany (Cercocarpus spp.), arrowleaf balsamroot (Balsamorhiza sagittata), western yarrow (Achillea millefolium), heartleaf arnica (Arnica cordifolia), bluebunch wheatgrass (Pseudoroegneria spicata), Sandberg bluegrass (Poa secunda), fescues (Festuca idahoensis and F. scabrella), prairie junegrass (Koeleria cristata), and sedges (Carex spp.). Like many other lupine species, this plant is highly toxic to sheep, and less toxic to cattle and horses. It contains teratogenic chemical compounds that can cause birth defects in calves if a pregnant cow consumes the plant during the early stage of gestation. Its toxicity comes from concentrated quinolizidine alkaloids. It does not appear to be toxic to wild animals such as white-tailed deer, which often eat it. Bighorn sheep feed on it in Montana, and Columbia ground squirrels eat its leaves and flowers. Many other small mammals and birds also consume parts of this plant.
