Astragalus bibullatus, the limestone glade milkvetch or Pyne's ground plum, is an endangered species of flowering plant that is endemic to the cedar glades of the central basin of Tennessee in the United States.

[2] The common name refers to Milo Pyne, who discovered the species in the 1980s, and the odd-looking smooth, reddish fruits that ripen on the ground and look superficially like plums (Prunus).

The foliage of Astragalus bibullatus looks similar to the more widespread cedar glade endemic, A. tennesseensis (Tennessee milkvetch).

A. tennesseensis fruits are greenish, hairy, and are more elongated (similar to an elf shoe) as is more typical for legumes.

Because of the small number of populations, A. bibullatus is threatened by habitat destruction.