Silvery Lupine

Lupinus argenteus

Silvery Lupine (Lupinus argenteus) is a native perennial of the pea family, with upright spikes of blue to violet pea flowers above leaves divided like the fingers of a hand. In the Black Hills it blooms from June into August, mostly in open pine and aspen woods and meadows of the northern and western Hills. The 1986 plant survey of Jewel Cave lists it, and the National Park Service records it at Wind Cave and Devils Tower.

Free photos from other sources

Silvery Lupine: Spike of blue and white pea flowers above hand-shaped leaves — Silvery Lupine (Lupinus argenteus). Bob Miller, CC BY 4.0, resized. Get it at the source

Silvery Lupine: Plant with pale purple flower spikes among green leaves — Silvery Lupine (Lupinus argenteus). Rory O'Shea, CC BY 4.0, resized. Get it at the source

Silvery Lupine: Very silvery leaves and a short flower head, held in a hand — Silvery Lupine (Lupinus argenteus). Seth G. Breeding, CC BY 4.0, resized. Get it at the source

Silvery Lupine: Leaves with narrow leaflets spreading like fingers — Silvery Lupine (Lupinus argenteus). Bob Miller, CC BY 4.0, resized. Get it at the source

Silvery Lupine: Pale lavender flowers and young hairy pods — Silvery Lupine (Lupinus argenteus). Bob Miller, CC BY 4.0, resized. Get it at the source

Silvery Lupine: Clump with several pale, nearly white flower spikes — Silvery Lupine (Lupinus argenteus). Rory O'Shea, CC BY 4.0, resized. Get it at the source

Quick facts
Family	Fabaceae · Pea
Status	Native perennial
Blooms	June into August, with a few into September
Height	20–70 cm (8–28 in)
Where	Open pine and aspen woods, forest openings, meadows and grassy hillsides
Also called	Lupine
Synonym	Lupinus parviflorus, Lupinus argenteus var. parviflorus, Lupinus argenteus var. rubricaulis, Lupinus argenteus var. argentatus, Lupinus floribundus, Lupinus spathulatus
Toxicity	It is poisonous to livestock, most of all the seeds and pods, and USDA ARS lists it among six lupines linked to crooked calf disease.
Traditional use	Vestal (1952) records that the Ramah Navajo put a poultice of crushed leaves on poison ivy blisters.

Roots, seeds & germination

Root: A woody crown at or just below the ground, with fibrous roots and occasional short rhizomes. Like most legumes it carries root nodules whose bacteria turn nitrogen from the air into a form plants can use.

Seed: A flattened, densely hairy pod 2–3 cm (about 1 in) long holds 2–6 tan to brown seeds. The pods ripen from late summer into fall and shatter when dry, throwing out the seeds.

Germination: The hard seed coat keeps water out, so stored seed needs scarification. A 2016 Native Plants Journal trial found it sprouted better after mechanical scarification, sulfuric acid, or a 60-second soak in water at 95 °C (203 °F), and USDA PLANTS says cold stratification is not needed.

How do you identify Silvery Lupine?

Look for leaves divided like a hand into 5 to 9 narrow leaflets, each 2–6 cm (¾–2½ in) long, all spreading from the tip of a long stalk, green to silvery with flat-lying hairs. The pea flowers, about 1 cm (⅜ in) long and blue to violet, are packed in whorls along a spike 5–25 cm (2–10 in) long, and the upper petal has a white or yellowish spot that turns reddish purple with age. Flattened, densely hairy pods follow in midsummer. Silverleaf Scurfpea has only 3 to 5 leaflets and small flowers in widely spaced clusters, and Canada Milkvetch and American Vetch have leaflets in pairs along a central stalk.

When does it bloom?

June into August, with a few into September.

Where does it grow?

Open ponderosa pine woods, aspen stands, forest openings, meadows, grassy hillsides, limestone outcrops and roadsides, at about 1,070–2,140 m (3,500–7,025 ft). It is local rather than everywhere: most herbarium specimens come from Lawrence County, the central limestone plateau in Pennington County, and Crook and Weston counties in the Wyoming Black Hills, with only a few from Custer and Fall River counties. The 1986 Jewel Cave survey lists it, and the National Park Service records it at Wind Cave and Devils Tower.