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coastal bush lupine, tree lupine, yellow bush lupine

summer lupine, western lupine

Habit Shrubs, usually 5–20 dm, green-glabrous or silver-hairy. Herbs, perennial, 12–8 dm, densely hairy to tomentose, gray to silver; rhizomes 3–7 mm diam.
Stems

ascending or erect, branched, woody.

ascending, spreading, or erect, branched.

Leaves

cauline;

stipules 8–12 mm;

petiole 2–3(–6) cm;

leaflets 5–12, blades 20–60 × 3–10 mm, adaxial surface glabrous.

cauline;

stipules not leaflike, green to silvery, 4–15 mm;

petiole 2–7 cm;

leaflets 7–9, blades 25–70 × 6–14 mm, adaxial surface pubescent.

Racemes

10–30 cm;

flowers whorled or not.

10–30 cm;

flowers ± whorled.

Peduncles

4–10 cm;

bracts deciduous, 8–10 mm.

3–7 cm;

bracts deciduous, 4–14 mm.

Pedicels

4–10 mm.

3–7 mm.

Flowers

14–18 mm;

calyx bulge or spur 0–1 mm, abaxial lobe entire, 5–7 mm, adaxial lobe 2-toothed, 5–9 mm;

corolla usually yellow, rarely lilac to purple, banner patch darker or not or white, banner glabrous abaxially, lower keel margins glabrous, adaxial margin ciliate from claw to tip.

10–18 mm;

calyx bulge or spur 0–1 mm, abaxial lobe entire or 3-toothed, 8–12 mm, adaxial lobe 2-toothed, 7–11 mm;

corolla purple, banner patch white or not, banner glabrous abaxially, keel upcurved, glabrous, banner ovate, wings wide, covering keel tip.

Legumes

4–7 cm, hairy.

3–4.5 cm, hairy.

Cotyledons

deciduous, petiolate.

deciduous, petiolate.

Seeds

8–12, black to tan, often striped lighter, 4–5 mm.

5–7, mottled brown, 4–7 mm.

2n

= 48.

Lupinus arboreus

Lupinus formosus

Phenology Flowering Apr–Jul.
Habitat Coastal bluffs, dunes, disturbed sand.
Elevation 0–100 m. (0–300 ft.)
Distribution
from FNA
CA; OR; WA; BC; Mexico (Baja California) [Introduced in South America (Argentina, Chile), Europe, Pacific Islands (New Zealand), Australia (including Tasmania)]
[WildflowerSearch map]
[BONAP county map]
from USDA
nw Mexico; California
[WildflowerSearch map]
[BONAP county map]
Discussion

Lupinus arboreus is known from the central California coast southward to northern Baja California; it was introduced as a sand binder and has become naturalized in northern California, Oregon, Washington, and southern British Columbia.

Lupinus arboreus grades into L. rivularis in the North Coast of California. Plants with yellow petals and sweet-smelling flowers are widely cultivated as a sand binder. Hairier plants from the western San Francisco Bay area with yellow banners and blue wings have been called var. eximius; plants with glabrous leaflets and purple petals have been called L. propinquus. Lupinus arboreus hybridizes with L. littoralis and probably other species. Seeds of L. arboreus species are toxic.

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

Varieties 2 (2 in the flora).

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

Key
1. Flowers 10–14 mm; stems 3–4 mm diam.
var. formosus
1. Flowers 16–18 mm; stems 5–7 mm diam.
var. robustus
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. 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
L. adsurgens, L. affinis, L. albicaulis, L. albifrons, 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. 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. formosus var. formosus, L. formosus var. robustus
Synonyms L. arboreus var. eximius, L. propinquus
Name authority Sims: Bot. Mag. 18: plate 682. (1803) Greene: Fl. Francisc., 42. (1891)
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