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)
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.