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golden banner, golden pea, mountain buck-bean, mountain golden-banner, mountain golden-pea, mountain thermopsis

Photo is of parent taxon

common thermopsis, slender goldenbanner

Habit Herbs delicate, 2–8(–10) dm, glabrate, appressed-pubescent, or thinly villous. Herbs 5–8(–10) dm, glabrate to sparsely appressed-pubescent.
Stems

slender, erect, solitary or clustered, moderately or few-branched, from woody rootstock or rhizomes;

branches ascending at 20–45º, weakly or moderately zigzag.

erect, clustered, several-branched, from woody rootstock;

branches weakly to moderately zigzag.

Leaves

stipules persistent, widely ovate or elliptic, 1.7–4.5 × 0.7–2.5 cm, base oblique to cuneate, apex acuminate or acute;

petiole 1–4 cm;

leaflet blades elliptic or obovate, 3.5–8 × 0.7–3(–5) cm, lateral veins 6–11 pairs, conspicuously net-veined abaxially or not, apex acute or obtuse, sometimes short-mucronate or emarginate, surfaces sparsely appressed-pubescent or glabrous.

petiole 3.2–4 cm;

leaflet blades broadly to narrowly elliptic or obovate, 4.5–6(–8) × 1.5–3(–5) cm, conspicuously net-veined abaxially, surfaces sparsely appressed-pubescent abaxially, glabrous adaxially.

Racemes

6–25-flowered, 4–25 cm;

flowers in whorls of 2 or 3 or scattered.

12–25 cm;

bracts narrowly elliptic.

Peduncles

2–8 cm;

bracts semipersistent, narrowly elliptic or elliptic to widely ovate, 6–10 × 2.5–6 mm.

Pedicels

3.5–5 mm, villosulous.

Flowers

1.6–2.2 cm;

calyx 9–11 × 5–8 mm at limb, lobes 3–5 mm, shorter than tube;

wings and keel petals asymmetrically oblong-elliptic;

ovary velutinous or densely appressed-pubescent;

ovules 10–16.

1.9–2.2 cm.

Legumes

ascending, straight, 4.5–6.5 × 0.4–0.6 cm, villosulous or appressed-pubescent.

appressed-pubescent.

Seeds

6–16, brown-black, oblong, 3.5–5 × 2.5–3 mm, beaked.

Thermopsis montana

Thermopsis montana var. ovata

Phenology Flowering May–Jun.
Habitat Moist soils, along streams and ditches, meadows, dry sagebrush plains.
Elevation 10–2000 m. (0–6600 ft.)
Distribution
from USDA
North America
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; MT; OR; WA; NF; QC
Discussion

Varieties 2 (2 in the flora).

The strictly erect fruits distinguish Thermopsis montana from T. gracilis and from the superficially similar T. divaricarpa. Intermediate populations and possible hybrids are discussed under T. divaricarpa by C. J. Chen et al. (1994).

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

Variety ovata is distinguished from var. montana by having a relatively robust habit, several-branched stems, and broader leaflets and bracts. It is introduced in Newfoundland and Quebec.

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

Key
1. Herbs 2–7 dm, appressed-pubescent to thinly villous; stems solitary or clustered, few-branched, from woody rootstock or rhizomes; leaflet blades not conspicuously net-veined abaxially; floral bracts elliptic to widely ovate.
var. montana
1. Herbs 5–8(–10) dm, glabrate to sparsely appressed-pubescent; stems clustered, several-branched, from woody rootstock; leaflet blades conspicuously net-veined abaxially; floral bracts narrowly elliptic.
var. ovata
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Thermopsis Fabaceae > subfam. Faboideae > Thermopsis > Thermopsis montana
Sibling taxa
T. californica, T. divaricarpa, T. fraxinifolia, T. gracilis, T. macrophylla, T. mollis, T. rhombifolia, T. robusta, T. villosa
T. montana var. montana
Subordinate taxa
T. montana var. montana, T. montana var. ovata
Synonyms T. rhombifolia var. montana T. montana subsp. ovata, T. gracilis var. ovata, T. macrophylla var. hitchcockii, T. montana var. hitchcockii, T. rhombifolia var. ovata
Name authority Nuttall in J. Torrey and A. Gray: Fl. N. Amer. 1: 388. (1840) (B. L. Robinson ex Piper) H. St. John: Torreya 41: 112. (1941)
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