Astragalus bibullatus was first described in 1987 by Rupert Charles Barneby and Edwin L. Bridges.[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). However, the species is a legume and is unrelated to plums, which are in the rose family.
The foliage of Astragalus bibullatus looks similar to the more widespread cedar glade endemic, A. tennesseensis (Tennessee milkvetch). However, the stem, leaves, and fruits of A. tennesseensis are all fuzzy, while they are smooth in A. bibullatus. Also, the flowers of A. bibullatus are pinkish purple in contrast to the yellow-white flowers of A. tennesseensis. The fruits are also quite different. A. tennesseensis fruits are greenish, hairy, and are more elongated (similar to an elf shoe) as is more typical for legumes. The flowers of A. bibullatus bloom in April and May, while the fruit ripens in May or June.
^Barneby, R. D. and E. L. Bridges (1987). A new species of Astragalus (Fabaceae) from Tennessee's Central Basin. Brittonia 39:358-363.
^Morris, A. B., R. S. Baucom, and M. B. Cruzan. 2002. Stratified analysis of the soil seed bank in the cedar glade endemic Astragalus bibullatus: evidence for historical changes in genetic structure. American Journal of Botany 89: 29-36.