Stinking Milkvetch

Astragalus praelongus var. praelongus

Family: Fabaceae (A Utah Flora – Leguminosae) – Pea Family

Perennial herbs; 4” to 2.9' (1 to 9 dm) tall

Leaves: alternate; compound; 1.2” to 8.8” (3 to 22 cm) long; 7 to 33 leaflets; leaflet 0.12” to 2” (3 to 50 mm) long, 0.08” to 0.96” (2 to 24 mm) wide

Flowers: 5 white petals (a banner, 2 wings and 2 keels – keel shorter than the wings); 5 toothed sepals; bisexual; 5-10 stamens; 1 pistil; 0.6” to 0.96” (15 to 24 mm) long

Pollinators: other Astragalus species are pollinated by insects (specifically bees, moths and butterflies)

Fruits: legume

Blooms in Arches National Park: April, May, June, July

Habitat in Arches National Park: in desert shrub and pinyon-juniper communities in clay and silt and seleniferous soils of Mancos Shale, Chinle Formation and Moenkopi Formation

Location seen: Balanced Rock, park road mile 12 near junction with Delicate Arch road, park road Salt Valley

Other: The genus name, “Astragalus”, is the Greek name for “legume”, and may be derived from “astragalos” which means “ankle bone” referring to the shape of the leaves or the pods. The species name, “praelongus”, means “growing very long or lance-like”.

This plant grows in selenium bearing soils and it may exude the unpleasant odor of selenium, hence the common name.

This family is ranked second to grasses in importance to people because species can fix nitrogen. However, some species, e.g., locoweeds and milkvetches, are poisonous due to selenium abstracted from the soil.