Astragalus applegatei is a rare species of milkvetch known by the common name Applegate's milkvetch. It is endemic to Klamath County, Oregon, where it is known from three populations, one of which is made up of only three plants. Much of the remaining habitat is seriously threatened by development, introduced plant species, and other forces. This is a federally listed endangered species of the United States. The native habitat of the plant is a seasonally wet floodplain with alkali soils, part of the Klamath Basin.