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Lupinus arbustus

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

chick lupine, wide-bannered lupine

Habit Herbs, perennial, 2–7 dm, green or gray-silky. Herbs, annual, 1–8 dm, sparsely to densely pubescent.
Stems

erect, ascending, or decumbent, branched.

ascending or erect, branched near base or middle, or unbranched, hollow, at least near base.

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;

petiole 3–15 cm;

leaflets 5–9(–11), blades 10–50 × 2–12 mm, adaxial surface glabrous.

Racemes

open, 3–18 cm;

flowers whorled.

4–60 cm;

flowers in crowded to widely spaced whorls.

Peduncles

2–5 cm;

bracts deciduous, 3–6 mm.

2–30 cm;

bracts persistent, reflexed, 3.5–12 mm.

Pedicels

1–7 mm.

0.5–5 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.

8–18 mm;

calyx appendages usually absent, sometimes present, abaxial lobe 5–11 mm, adaxial lobe 2–6 mm;

corolla white to dark yellow, pink to dark rose, or lavender to purple, lower wing margins sometimes ciliate, upper margins usually ciliate near claw, upper keel margins usually ciliate near claw, lower margins sometimes ciliate but not as densely.

Legumes

2–3 cm, silky.

1–1.8 cm, pubescent.

Cotyledons

deciduous, petiolate.

persistent or deciduous (leaving circular scar), disclike, sessile.

Seeds

3–6, tan, 5–6 mm.

2, tan to brown, usually mottled, ridged or smooth.

Lupinus arbustus

Lupinus microcarpus

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 North America; nw Mexico; South America
[WildflowerSearch 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 3 (3 in the flora).

Lupinus microcarpus is highly variable and with varieties intergrading.

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

Key
1. Wings broadly elliptic, persistent and becoming translucent, upper and usually lower margins ciliate near claw; lower keel margins ciliate near claw; calyx appendages 1–2 mm.
var. horizontalis
1. Wings linear to oblanceolate, withering, not becoming translucent, upper margins usually ciliate near claw, lower rarely; lower keel margins sometimes ciliate near claw or sparsely so; calyx appendages usually absent.
→ 2
2. Calyx and flower bracts with long shaggy hairs; legumes usually erect or spreading.
var. microcarpus
2. Calyx and flower bracts with few short and appressed, or long and spreading hairs; legumes usually secund, sometimes spreading.
var. densiflorus
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. 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. 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. microcarpus var. densiflorus, L. microcarpus var. horizontalis, L. microcarpus var. microcarpus
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) Sims: Bot. Mag. 50: plate 2413. (1823)
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