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Lupinus pusillus

intermountain lupine, low lupine, rusty lupine

summer lupine, western lupine

Habit Herbs, annual, 0.5–2 dm, sparsely pubescent to pilose, hairs more than 1 mm. Herbs, perennial, 12–8 dm, densely hairy to tomentose, gray to silver; rhizomes 3–7 mm diam.
Stems

short and tufted or erect, branched from base or near middle.

ascending, spreading, or erect, branched.

Leaves

cauline, often crowded near base;

stipules well developed;

petiole 1–9 cm;

leaflets 5–9, blades 10–40 × 5–10 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

8–12-flowered, 2–11 cm, shorter than or slightly exceeding foliage;

flowers spirally arranged.

10–30 cm;

flowers ± whorled.

Peduncles

0–3.5 cm;

bracts persistent, straight, 2–5 mm.

3–7 cm;

bracts deciduous, 4–14 mm.

Pedicels

1–3.5 mm.

3–7 mm.

Flowers

5–12 mm;

calyx abaxial lobe entire, 5–6 mm, adaxial lobe cleft, 2.5–4 mm;

corolla vivid blue, sometimes paler or white, sometimes bicolored, banner spot white or yellowish, keel glabrous.

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

1.5 cm, constricted between seeds, thinly pilose to coarsely hirsute.

3–4.5 cm, hairy.

Cotyledons

persistent, disclike, sessile.

deciduous, petiolate.

Seeds

2, wrinkled or ridged.

5–7, mottled brown, 4–7 mm.

Lupinus pusillus

Lupinus formosus

Distribution
from USDA
w North America; c North America
[WildflowerSearch map]
[BONAP county map]
from USDA
nw Mexico; California
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 3 (3 in the flora).

Lupinus pusillus is a highly variable species, with the varieties intergrading.

(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. Peduncles 0–1 cm; racemes shorter than foliage; flowers 6–8 mm.
var. intermontanus
1. Peduncles usually 1–3.5 cm; racemes equal to or longer than foliage; flowers 7–12 mm.
→ 2
2. Pedicels and calyx tubes strigose.
var. pusillus
2. Pedicels and calyx tubes glabrous.
var. rubens
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. 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. 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. pusillus var. intermontanus, L. pusillus var. pusillus, L. pusillus var. rubens
L. formosus var. formosus, L. formosus var. robustus
Name authority Pursh: Fl. Amer. Sept. 2: 468. 1814[1813] Greene: Fl. Francisc., 42. (1891)
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