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Crescent Milk-vetch Astragalus amphioxys


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Crescent Milk-vetch (Astragalus amphioxys var. amphioxys is shown)
credit: Stan Shebs/CCSA

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Alternate name: Aladdin's-slippers

Family: Fabaceae, Pea view all from this family

Description A tufted, grayish, hairy plant with pinnately compound leaves and lavender, pink, or red-violet pea flowers in short racemes.
Habit: native annual or perennial herb.
Height: 2-15 in (5-38 cm)
Leaf: small, alternate, odd-pinnate, arching, to 0.5 in (12 mm) long; 7-21 leaflets, ovate, somewhat erect, folded, to 1 in (25 mm) long and 0.4 in (10 mm) wide.
Flower: magenta to lavender, fading to pale purple to blue-gray, rarely white, 0.7-1.25 in (17-32 mm) long, with 5 lobed, unequal petals (banner, 2 wings, 2 keels); in spreading cluster of around 5 flowerheads.
Fruit: pod, curved, pointed at both ends, crescent-shaped, 0.75-2 in (2-5 cm) long.

Warning All plants in the genus Astragalus are potentially toxic to humans and animals if ingested, causing a disorder called locoism. The milk from an animal that has ingested Astragalus plants may also be toxic. Sensitivity to a toxin varies with a personís age, weight, physical condition, and individual susceptibility. Children are most vulnerable because of their curiosity and small size. Toxicity can vary in a plant according to season, the plantís different parts, and its stage of growth; and plants can absorb toxic substances, such as herbicides, pesticides, and pollutants from the water, air, and soil.

Flower January to June.

Habitat Sandy or gravelly soil in deserts, arid grasslands, desert shrubland, pi“on and juniper communities, dry valley floors, hillsides, desert playas.

Range Native to Arizona and southern Nevada, east to western Colorado, central New Mexico, and extreme western Texas.

Discussion Four varieties are proposed. Crescent Milk-vetch can be distinguished from many similar species by its pod, which has only one chamber and a lower seam that lies in a groove rather than forming a prominent ridge. Among the Zuni Indians of New Mexico, the fresh or dried root of this plant was chewed by a medicine man before sucking the venom from a snakebite.