Sophora nuttalliana or Vexibia nuttalliana
(Silky Sophora)
Family: Fabaceae (Pea)
  
Sophora nuttalliana looks very much like an Oxytropis sp., with a raceme of flowers with pointed keels. Look inside the flower, however, and you'll find the stamen filaments are separate, while Oxytropis spp. have united stamens. Flowers sometimes have a purple calyx. Fruits of Silky Sophora are called loments and are pods with constrictions around the seeds. Silky Sophora is most commonly found on sandy soils on the plains.

Compare to Oxytropis sericea, which has united stamens and a plump fruit, held upright and without constrictions.

Vegetation zone:  Plains (3400 - 7500 ft.)
Time of bloom:  May - July
Origin:  Native
Eastern Colorado Wildflowers