Lupinus oreganus
Muhlenbergia 7: 89, fig. 14. 1911.
Herbs, perennial, 3–10 dm, appressed-silky, green but sometimes hair is tawny; rhizomatous. Cotyledons deciduous, petiolate. Stems erect, usually unbranched. Leaves cauline (few and large) and basal (persistent until after anthesis); stipules 11 mm; petiole 5–20 cm; leaflets (7–)9–11(or 12), blades 20–50(–80) × 5–12 mm, abaxial surface with long, appressed hairs, especially on margins and veins, adaxial surface usually glabrous. Peduncles 11–18 cm; bracts deciduous, 5 mm. Racemes loose, 11–40 cm; flowers spirally arranged or whorled. Pedicels 5–12 mm. Flowers fragrant, 8–13 mm; calyx bulge or spur 0–1 mm, abaxial lobe entire, 6 mm, adaxial lobe notched, 4–6 mm; corolla blue to purple, yellowish, or creamy white, banner distinctly ruffled, markedly concave on lateral face, banner glabrous or sparsely pubescent abaxially, wings glabrous, keel curved upward, lower keel margins glabrous, adaxial margin glabrous. Legumes 2–3 cm, glabrous. Seeds 4 or 5. 2n = 48.
Phenology: Flowering Apr–Jun.
Habitat: Dry hills, open ground, rocky, well-drained soils, sometimes serpentine, upland prairies, ecotones between grasslands and forests.
Elevation: 70–900 m.
Distribution
Oreg., Wash.
Discussion
Lupinus oreganus is known from west of the Cascades from Douglas County, Oregon, northward to Lewis County in Washington. Historically, it was found in British Columbia in Victoria on Vancouver Island but has not been seen there since the 1920s and is now considered extirpated there.
Lupinus oreganus is a food plant for Fender’s Blue Butterfly, listed by ESA as endangered. Lupinus oreganus (as var. kincaidii) is listed as endangered in Washington. It is also listed as extirpated by the Committee on the Status of Endangered Wildlife in Canada and the Species at Risk Act.
Selected References
None.