Scientific Family
Fabaceae
Synonyms
Astragalus allochrous, Astragalus wootonii
Other common names
Wooton loco
halfmoon milkvetch
rattleweed
locoweed
Plant type
Forbs and Subshrubs
Origin
Native
Lifecycle
Biennial or annual
Height
3 to 12 inches
Riparian
Yes
Herbage covered with short stiff hairs along the stem; several or many flower clusters; pods long and enlarged. When dry, the seeds in the pod break loose and rattle, giving it the name rattleweed.
Ascending to trailing annual or biennial; leaves are compound with narrow leaflets (1/8 inch wide) that are hairy on the underside; flowers are bright to light purple, <1/2 inch long; fruits are 1-celled greatly inflated pods.
Habitat
Found on grasslands, chaparral, woodlands and riparian areas.
Plant Community
Riparian
Pinyon Juniper Woodlands
Interior Chaparral
Grasslands
Low elevation
3000
High elevation
7100
Flower Characteristics
Flowers less than 3/8 inch long; keel (two lower) petals arched; flower clusters of 5 to 10 flowers; sepals 2/3 as long or longer than the flower petals.
Flower color
Bright to light purple
Flower shape
Other
Tubular
Yes
First bloom month
March
Last bloom month
July
Flower clusters
Elongated
Leaf and Stem Characteristics
Leaves 1-1/2 to 4 inches long with 11 to 23 narrow to oblong leaflets, 1/5 to 1 inch long.
Leaf type
Compound
Leaf color
Green
Leaf shape
Narrow
Leaf margin
Smooth
Leaves clasp
No
Leaf hairs
Leaves
Spines
No
Fruit and Seed Characteristics
Greatly inflated pods, thin-walled, 3/5 to 1 inch long, broadly ovate and very asymmetric, much more strongly curved on the lower (dorsal) side than on the upper (ventral) side.
Fruit type
Pod
Fruit color
Reddish-brown