Thermopsis gracilis
slender goldenbanner, slender thermopsis
slender, erect, solitary or clustered, many-branched, from woody rootstock or rhizomes;
branches spreading at 30–70º, moderately to strongly zigzag.
stipules persistent, asymmetrically ovate-elliptic, 2.5–3.5 × 1.5–3 cm, base cuneate to cordate, apex acuminate;
petiole 2.5–4(–5) cm;
leaflet blades elliptic to obovate or rhombic, 3–6(–8) × 2–3.2 cm, lateral veins 6–9 pairs, conspicuously net-veined abaxially, apex acute, obtuse, or emarginate, surfaces glabrous.
7–30-flowered, 12–20(–30) cm;
flowers scattered.
4–9(–11) cm;
bracts semipersistent, ovate, 6–8 × 3–5 mm.
6–16 mm, glabrous or sparsely villous.
2–2.3 cm;
calyx 8–10 × 7–8 mm at limb, lobes 2–3 mm, much shorter than tube;
wing petals elliptic, keel petals asymmetrically oblong-elliptic;
ovary sparsely villous;
ovules 9–14.
irregularly divergent, straight, 3–6 × 0.4–0.6 cm, inconspicuously pubescent.
2–8, tan, oblong, 3–4 × 2 mm, short-beaked.
= 36.
Thermopsis gracilis
Thermopsis gracilis is readily distinguished from the closely allopatric T. californica and T. montana by its divergent fruits, spreading branches, and glabrous to sparsely pubescent foliage. The species is most closely related to T. robusta, which also has divergent fruits but which differs in its very robust habit, densely pilose vestiture, and longer calyx lobes.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
Flora NW
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
