Astragalus is a large genus which also has pea-like flowers (“Pea Flower Arrangement” 11-20-2017). Its members are often very similar and difficult to distinguish. I believe these plants, growing in May along Washoe County (Nevada) Road 8A just east of the California/Nevada border, is sickle milkvetch (Astragalus curvicarpus). There are several subspecies of A. curvicarpus.
Sickle milkvetch stems arise from a buried root crown. The stems are spreading to ascending and are covered with hairs.
The pinnately compound leaves of sickle milkvetch have 9 to 17 oblanceolate leaflets with obtuse or notched tips.
Inflorescences of uncrowded racemes (unbranched with the flowers maturing from the bottom upward) are located at the end of the stems. The pea-like sickle milkvetch flowers are white aging to a yellowish white. The banner petal is recurved. The calyx (sepals collectively) lobes are triangular and short. The calyx is covered with short black hairs.
The sickle milkvetch fruit is a single-chambered sickle or coiled pod, tapered to a point at both ends. The pod usually has a smooth surface. The fruit shape is reflected in the common names which, in addition to sickle milkvetch, also include curvepod milkvetch and coiled milkvetch.
A native perennial, sickle milkvetch is found in Oregon, Nevada, California and Idaho between 3,100 and 9,200 feet in elevation. Its habitat is porous, gravelly soils in the sagebrush desert.
Astragalus comes from the Greek word for anklebone. The plural of the Greek word also means “dice”. The genus name refers to the sounds made by shaking dice or gaming bones and is similar to the rattling of seeds in the dry pod. The species designation comes from the Latin “curvus” meaning curve and “carpus” meaning wristbone.