Astragalus microcymbus is a species of flowering plant in the legume family known by the common name skiff milkvetch. It is endemic to Colorado in the United States, where it is known from Gunnison County and the edge of Saguache County. This perennial herb grows up to 30 centimeters in height. In May and June it produces many white flowers with purple-tinged petals. The species name means "little boat", referring to the legume pods, which resemble skiffs. It grows in sagebrush habitat and sagebrush-juniper mixed habitat.