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Lupinus arbustus

grassland lupine (ssp. neolaxiflorus), long-spur lupine, Montana lupine (ssp. pseudoparviflorus), spur lupine

evergreen lupine, silver bush lupine, silver lupine, white-leaf bush lupine

Habit Herbs, perennial, 2–7 dm, green or gray-silky. Subshrubs or shrubs, rarely perennial herbs, (1–)2–50 dm, usually silvery, sometimes greenish.
Stems

erect, ascending, or decumbent, branched.

decumbent to erect, clustered, branched or unbranched.

Leaves

cauline and basal;

stipules 4–9 mm;

petiole 2–16 cm;

leaflets 7–10(–13), blades 20–70 × 3–15 mm, adaxial surface strigose.

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.

Racemes

open, 3–18 cm;

flowers whorled.

4–40 cm, rachis usually deciduous or semideciduous;

flowers usually spirally arranged or loosely whorled.

Peduncles

2–5 cm;

bracts deciduous, 3–6 mm.

5–13 cm;

bracts deciduous, 4–24 mm.

Pedicels

1–7 mm.

3–10 mm.

Flowers

8–14 mm;

calyx spur distinct, 1–3 mm, abaxial lobe 3-toothed, 2.5–5 mm, 1–3 mm, adaxial lobe 2-toothed, 2–4 mm;

corolla blue, purple, pink, white, or yellowish, banner patch white, yellowish, or absent, banner hairy abaxially, wings with dense hair patch outside near tip, lower keel margins glabrous, adaxial margin ciliate.

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

2–3 cm, silky.

3–5 cm, hairy.

Cotyledons

deciduous, petiolate.

deciduous, petiolate.

Seeds

3–6, tan, 5–6 mm.

4–9, mottled tan, 4–6 mm.

Lupinus arbustus

Lupinus albifrons

Phenology Flowering May–Jul.
Habitat Open sagebrush scrub or mixed-conifer forests.
Elevation 1500–3000 m. [4900–9800 ft.]
Distribution
from FNA
CA; ID; MT; OR; UT; WA; BC
[WildflowerSearch map]
[BONAP county map]
from USDA
w United States; n Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Lupinus arbustus is known from the Cascade and Klamath ranges, San Gabriel Mountains, Sierra Nevada, and the Great Basin area in California; Owyhee Desert in Idaho and Oregon; eastern Washington and western Montana; and western Juab and Tooele counties, Utah.

Lupinus arbustus is separated from the argenteus group by the presence of hairs on the corolla wings. Recognition of subspecies and varieties of this already complex species leads to precarious separation among taxa.

Lupinus variegatus A. Heller (1912, not Poiret 1814) is an illegitimate name that pertains here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Shrubs, 5–50 dm.
→ 2
2. Flowers 14–18 mm; leaves greenish hairy.
var. hallii
2. Flowers 10–14 mm; leaves silver-silky.
→ 3
3. Inflorescence bracts 4–8 mm; coastal California, s Oregon.
var. albifrons
3. Inflorescence bracts 10–24 mm; San Francisco Bay region, Central Coast, n Channel Islands, California.
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.
var. austromontanus
5. Plants woody toward base; racemes 6–12 ­cm; San Bernardino and San Gabriel mountains, California.
var. johnstonii
4. Flowers 10–16 mm.
→ 6
6. Petioles to 12 cm; Sonora Desert, California.
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.
var. abramsii
7. Pubescence appressed-silvery, not woolly or shaggy; subshrubs 2–4 dm; n, s Coast Ranges, n Sierra Nevada Foothills, Cali­fornia, Oregon.
var. collinus
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Lupinus Fabaceae > subfam. Faboideae > Lupinus
Sibling taxa
L. adsurgens, L. affinis, L. albicaulis, L. albifrons, L. andersonii, L. angustiflorus, L. antoninus, L. apertus, L. arboreus, L. arcticus, L. argenteus, L. arizonicus, L. benthamii, L. bicolor, L. brevicaulis, L. breweri, L. cervinus, L. chamissonis, L. citrinus, L. concinnus, L. constancei, L. covillei, L. croceus, L. dalesiae, L. diffusus, L. duranii, L. elatus, L. elmeri, L. excubitus, L. flavoculatus, L. formosus, L. fulcratus, L. gracilentus, L. grayi, L. guadalupensis, L. havardii, L. hirsutissimus, L. huachucanus, L. hyacinthinus, L. kingii, L. kuschei, L. lapidicola, L. latifolius, L. lepidus, L. leucophyllus, L. littoralis, L. longifolius, L. ludovicianus, L. luteolus, L. magnificus, L. malacophyllus, L. microcarpus, L. nanus, L. neomexicanus, L. nevadensis, L. nipomensis, L. nootkatensis, L. obtusilobus, L. odoratus, L. onustus, L. oreganus, L. pachylobus, L. padrecrowleyi, L. peirsonii, L. perennis, L. polyphyllus, L. pratensis, L. pusillus, L. rivularis, L. sabineanus, L. sericatus, L. sericeus, L. shockleyi, L. sierrae-blancae, L. sparsiflorus, L. spectabilis, L. stiversii, L. subcarnosus, L. succulentus, L. sulphureus, L. texensis, L. tidestromii, L. tracyi, L. truncatus, L. uncialis, L. villosus, L. westianus
L. adsurgens, L. affinis, L. albicaulis, L. andersonii, L. angustiflorus, L. antoninus, L. apertus, L. arboreus, L. arbustus, L. arcticus, L. argenteus, L. arizonicus, L. benthamii, L. bicolor, L. brevicaulis, L. breweri, L. cervinus, L. chamissonis, L. citrinus, L. concinnus, L. constancei, L. covillei, L. croceus, L. dalesiae, L. diffusus, L. duranii, L. elatus, L. elmeri, L. excubitus, L. flavoculatus, L. formosus, L. fulcratus, L. gracilentus, L. grayi, L. guadalupensis, L. havardii, L. hirsutissimus, L. huachucanus, L. hyacinthinus, L. kingii, L. kuschei, L. lapidicola, L. latifolius, L. lepidus, L. leucophyllus, L. littoralis, L. longifolius, L. ludovicianus, L. luteolus, L. magnificus, L. malacophyllus, L. microcarpus, L. nanus, L. neomexicanus, L. nevadensis, L. nipomensis, L. nootkatensis, L. obtusilobus, L. odoratus, L. onustus, L. oreganus, L. pachylobus, L. padrecrowleyi, L. peirsonii, L. perennis, L. polyphyllus, L. pratensis, L. pusillus, L. rivularis, L. sabineanus, L. sericatus, L. sericeus, L. shockleyi, L. sierrae-blancae, L. sparsiflorus, L. spectabilis, L. stiversii, L. subcarnosus, L. succulentus, L. sulphureus, L. texensis, L. tidestromii, L. tracyi, L. truncatus, L. uncialis, L. villosus, L. westianus
Subordinate taxa
L. albifrons var. abramsii, L. albifrons var. albifrons, L. albifrons var. austromontanus, L. albifrons var. collinus, L. albifrons var. douglasii, L. albifrons var. hallii, L. albifrons var. johnstonii, L. albifrons var. medius
Synonyms L. arbustus subsp. calcaratus, L. arbustus var. montanus, L. arbustus subsp. neolaxiflorus, L. arbustus subsp. pseudoparviflorus, L. arbustus subsp. silvicola, L. caesius, L. caudatus var. submanens, L. caudatus var. subtenellus, L. elegantulus, L. inyoensis var. demissus, L. laxiflorus var. calcaratus, L. laxiflorus var. cognatus, L. laxiflorus var. elmerianus, L. laxiflorus var. lyleianus, L. laxiflorus var. pseudoparviflorus, L. laxiflorus var. silvicola, L. laxiflorus var. villosulus, L. lyleianus, L. mucronulatus var. umatillensis, L. multitinctus, L. noldekeae, L. proteanus, L. pseudoparviflorus, L. silvicola, L. wenatchensis, L. yakimensis
Name authority Douglas: Edwards’s Bot. Reg. 15: plate 1230. (1829) Bentham: Edwards’s Bot. Reg. 19: plate 1642. (1834)
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