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Plants & Animals

Highlights - Plant Materials Program

Slimflower Scurfpea (Psoralidium Tenuiflorum)

Scientific Name: Psoralidium tenuiflorum (Pursh) Rydb. Formerly Psoralea tenuiflora
Family Name: Pea (Fabaceae)
Common Name: slimflower scurfpea, wild alfalfa

Morphological Characteristics:
Habit - native perennial legume, deeply taprooted and rhizomatous, with many branched, erect stems, from a woody crown, 30 to 60 cm (12 to 24 in.) tall.
Leaves - alternate, palmately compound, mostly 3 to 5 leaf-segments, leaflets linear to rounded, 1 to 4 cm (0.4 to 1.6 in) long and less than 0.5 in (13 mm) wide, upper surface mostly smooth and glabrous and appressed-hairy beneath, leaves and stems covered with small, scale-like glands or scurf.
Flowers – typical pea-like blossoms in elongated clusters on small branches off the leaf stalk; the calyx tube at the base of each bloom is greenish to dark brown in color, and the flower petals (corolla) are light blue to purple and sometimes whitish, 4 to 7 mm (0.15 to 0.28 in) long, slightly flared and keel-lipped.
Pea Pods– smooth and glandular-dotted, broader at the base than tip, and tapering to a short, conical beak, 7 to 8 mm (0.28 to 0.31 in) long, 1-seeded.
Fruit – legume seed, mostly spherical (globose), olive to dark brown, 4 to 5 mm (0.15 to 0.2 in) long.

Bloom Period/Seed Maturity: flowers June to August, and seed matures July to September; the entire plant disarticulates at the crown following maturity and tumbles with the wind.

Distribution & Habitat: found in nearly all of Montana and Wyoming east of the Continental Divide, mainly as scattered individuals in upland grass communities, but may be present in large numbers on over-grazed rangeland; prefers sandy or light-textured soils; dry plains, prairies, and open woods.

 Picture of Slimflower Scurfpea