Subshrubs or shrubs, rarely perennial herbs, (1–)2–50 dm, usually silvery, sometimes greenish. Cotyledons deciduous, petiolate. Stems decumbent to erect, clustered, branched or unbranched. Leaves cauline, clustered near base or not; stipules 6–20 mm; petiole 1–8(–12) cm; leaflets 6–10, blades 10–45 × 4–18 mm, surfaces hairy. Peduncles 5–13 cm; bracts deciduous, 4–24 mm. Racemes 4–40 cm, rachis usually deciduous or semideciduous; flowers usually spirally arranged or loosely whorled. Pedicels 3–10 mm. Flowers 10–18 mm; calyx bulge or spur 0–1 mm, abaxial lobe entire or 3-toothed, 6–10 mm, adaxial lobe deeply divided, 6–8 mm; corolla violet to lavender, patch usually yellow, rarely white, turning purple, banner usually hairy abaxially, rarely glabrous, keel usually unlobed proximally, adaxial margin usually ciliate middle to tip, abaxial margins glabrous. Legumes 3–5 cm, hairy. Seeds 4–9, mottled tan, 4–6 mm.
Distribution
w United States, n Mexico.
Discussion
Varieties 8 (8 in the flora).
Lupinus albifrons is the most common shrubby lupine in western North America. The combination of silver-pubescent leaves, banners that are pubescent abaxially, and keels that are usually ciliate will separate it from the coastal L. arboreus and the dune loving L. chamissonis. The desert L. excubitus is separated by petiole length, raceme rachis persistence and size, elevation, and distribution. Some of the varieties (austromontanus, collinus, and medius) are woody at base but can appear herbaceous.
Selected References
None.
Lower Taxa
Key
| 1 | Shrubs, 5–50 dm. | > 2 |
| 2 | Flowers 14–18 mm; leaves greenish hairy. | Lupinus albifrons var. hallii |
| 2 | Flowers 10–14 mm; leaves silver-silky. | > 3 |
| 3 | Inflorescence bracts 4–8 mm; coastal California, s Oregon. | Lupinus albifrons var. albifrons |
| 3 | Inflorescence bracts 10–24 mm; San Francisco Bay region, Central Coast, n Channel Islands, California. | Lupinus albifrons var. douglasii |
| 1 | Subshrubs (occasionally semi-herbaceous and woody at base), 1–7(–10) dm. | > 4 |
| 4 | Flowers 14–18 mm. | > 5 |
| 5 | Plants herbaceous toward base; racemes 14–40 cm; Tehachapi Mountains, California, southward. | Lupinus albifrons var. austromontanus |
| 5 | Plants woody toward base; racemes 6–12 cm; San Bernardino and San Gabriel mountains, California. | Lupinus albifrons var. johnstonii |
| 4 | Flowers 10–16 mm. | > 6 |
| 6 | Petioles to 12 cm; Sonora Desert, California. | Lupinus albifrons var. medius |
| 6 | Petioles 3–8 cm; cismontane California. | > 7 |
| 7 | Pubescence woolly to shaggy; shrubs or subshrubs 2–10 dm; Santa Lucia Mountains, Monterey County, California. | Lupinus albifrons var. abramsii |
| 7 | Pubescence appressed-silvery, not woolly or shaggy; subshrubs 2–4 dm; n, s Coast Ranges, n Sierra Nevada Foothills, California, Oregon. | Lupinus albifrons var. collinus |