Thermopsis macrophylla Hook. & Arn.

  • Authority

    Isely, Duane. 1981. Leguminosae of the United States. III. Subfamily Papilionoideae: tribes Sophoreae, Podalyrieae, Loteae. Mem. New York Bot. Gard. 25 (3): 1-264.

  • Family

    Fabaceae

  • Scientific Name

    Thermopsis macrophylla Hook. & Arn.

  • Description

    Species Description - Deeply velutionous to glabrate, silvery-cinereous to green, small and bushy, or tall and robust herb with solitary or clustered, erect, branched stems 3—10 (-20) dm. Pubescence abundant or scant, usually of flexuous or curved hairs, that of stems mostly spreading, of the leaves, spreading, incurved or becoming tangled (-straight and appressed in var argentata). Leaves usually monomorphic; petioles 1-4 dm; leaflets broadly ovate or elliptic to oblanceolate, 2.5-6 cm, ca. 1.8-3.2 r, less pubescent above than below. Stipules sharply diminishing upwards or not, sometimes grading into raceme bracts, 1-5 cm and to 3 cm broad. Racemes often terminal and solitary, 1-5 dm, with 6-many, ascending flowers 15-21 mm; bracts .5-1.5 cm, broadly ovate and obtuse, to lanceolate and acute or acuminate, flat or folded. Flowering pedicels initially ca. 5 mm, then elongating. Calyx 7-10 mm, lobes 2-5 mm, ± or < tube. Ovary stipitate 1-2 mm; body usually densely villous (-glabrous) with hairs to 1 mm; style glabrous; ovules 5-12. Legume straight and ascending or erect, or arcuate-divergent, stipitate 1—2(—5) mm, often irregularly margined due to poor seed set, 3-6(-7) cm x 6-8(-9) mm; valves mildly expressed over seeds, pubescent (-glabrate).

  • Discussion

    Thermopsis macrophylla, except for the shrubby local Pickeringia, is the only native legume with palmate leaves and free stamens in the Pacific states. The following regional varieties are morphologically confluent, and it is difficult to name some of them if origin is not known.

  • Distribution

    Pacific states, cismontane from Ventura co, California to c Washington; also of Cascades in n California and isolated in interior San Diego co. Slightly in cultivation. Golden-pea, False lupine.

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