Silvery lupine is a widespread lupine, and exhibits many variations in its characteristics, which has resulted in its division into about a dozen varieties. Because of this variation, I presume that at least some of the varieties may be classified with different species at some point in the future (one example is Lupinus argenteus var. heteranthus, which may have been reclassified to L. caudatus, the Kellogg's spurred lupine.).
Silvery lupine is an upright perennial with one to several green or purplish stems from 1.5-7 dm in height. Typically, one can identify this species from a distance as it often lacks basal leaves during flowering. If they are present when in bloom, the petioles will be less than three times the length of their leaflets. The compound-palmate leaves are usually found on the stems. The petioles of the leaves range from 2-8 cm long, with the 6-10 leaflets ranging from 2-7 cm long and 3-18 mm wide. The individual leaflets are linear-oblanceolate/elliptic to broadly oblanceolate in shape.
The racemes are typically solitary and terminal, arising above the highest leaves. Occasionally, smaller secondary racemes may arise from lateral branches. The flowers are scattered with the petals usually blue, sometimes lavender, pink, puple, or white. The banner, which is 4-14 mm long, has a yellowish-white eye. The banner is sparsely, if at all, haired on its back. The upper calyx lobe would usually cover any such hairs.The wing petals are from 5-14 mm long with the keel about as long as the wings. The calyx is variable, often spurred, but also frequently lacking a spur.The calyx is 4.5-10 mm in lengthm typically covered with appressed hairs. In south-central Oregon, bloomtime may range from mid-May to well into September and October.
Silvery lupine may be found in open ponderosa pine forests, throughout the sagebrush plains, and into the juniper forest of the intermountain west.
Silvery lupine may be found widely across the Great Basin and northeastward into the Rocky Mountains of Montana and Wyoming.
- - -