Duration: Perennial
Nativity: Native
Lifeform: Forb/Herb
General: Sour-smelling perennial herb, 10-90 cm tall, from a woody caudex; stems several, erect or ascending; herbage nearly glabrous.
Leaves: Alternate and pinnately compound, 3-22 cm long, with 7-33 leaflets per leaf; leaflets obovate to oblong, 3-50 mm long and 2-24 mm wide, with entire margins, the upper surface hairless and the the lower surface sparingly strigose; stipules 2-9 mm long, distinct.
Flowers: Mostly cream-colored, in crowded racemes 3-13 cm long, with the flowers nodding slightly at maturity; flowers 15-24 mm long, with pea-flower morphology (papilionaceous), with a wide upper petal called the banner, two smaller lateral petals called the wings, and a boat-shaped lower petal called the keel which contains the style and stamens. Petals cream-colored or rarely pink-tinged, the keel petal often purple-tipped; sepals 5, greenish to yellowish and glabrous or thinly strigose, united into a tube 5-7 mm long, topped with 5 narrow teeth, 1-6 mm long.
Fruits: Pods erect to declined (pointing upward to downward), ellipsoid, ovoid or subglobose and somewhat inflated, 2-4 cm long and 5-25 mm wide, leathery-woody, subunilocular, and strigose or glabrous; with or without a stipe (short stalk at the base of the pod,
Ecology: Found in desertscrub and pinyon-juniper woodland communities, usually in fine-grained selenium-rich soils derived from geologic formations such as Chinle, Moenkopi, and Mancos shale, from 3,000-8,000 ft (914-2438 m); flowers April-July.
Distribution: s NV to c AZ, east to sw CO, NM, and w TX.
Notes: This is a stinky, selenium-accumulating perennial Astragalus (the smell goes away once the plant dries, so if you notice a smell, write it in your field notes). Look for the often robust growth form (formal descriptions state this species grows up to 1 meter tall, but I've seen it 2 meters tall growing in a wash bottom); nearly hairless stems and leaves; congested racemes of 10-33 cream-colored flowers, sometimes with a purple tip on the keel petals; and leathery-woody seed pods which are somewhat inflated and unilocular (cut it in half cross-wise and there is only one chamber). There are 3 varieties: var. lonchopus occurs in the four-corners region and has seed pods on stipes 4-8 mm long (the stipe is a stalk at the base of the pod, above the calyx attachment point), and linear leaflets 7-9 times as long as wide. Var. praelongus has seed pods without stipes, or with short stipes less than 3 mm long, and broader leaflets, 2-7 times as long as wide. Some treatments also recognize var. ellisiae, which is similar to var. praelongus but has narrower seed pods, less than 1 cm wide.
Ethnobotany: Ramah Navajo used it as a ceremonial emetic.
Etymology: Astragalus comes from the Greek astragalos, ankle bone, an early name applied to some plants in this family because of the shape of the seeds; praelongus means very tall.
Editor: AHazelton 2017
