Astragalus bibullatus is a perennial herb that is endemic to Tennessee's Central Basin in the southeastern United States. This species occurs in limestone glades in the Central Basin which are located in the Metropolitan Nashville area, where development is occurring at a rapid pace. There are several occurrences on private land which are threatened by development and land clearing. In addition, the species requires active management to limit encroachment by more competitive, often woody, plants. This species qualifies as Vulnerable due to its small extent of occurrence (537 km²) and area of occupancy (32 km²), seven locations, and ongoing threats that are inferred to cause continuing declines in habitat quality.

Astragalus bibullatus occurs in the southeastern United States and is endemic to cedar glades in the Central Basin Section of the Interior Low Plateau of Tennessee in Rutherford County. The species' entire range is within the Stones River Watershed (USFWS 2011). Range extent was calculated using extant occurrences. One site, last surveyed in 1999, was extirpated by rock fill excavation activities at the site (NatureServe Network 2021). An additional introduced site is extirpated and last surveyed in 2006 (NatureServe Network 2021, USFWS 2011). Two sites with plants last collected in 1881 and 1948 are believed to be extirpated, the habitat no longer exists at one site and the other was inundated with water during the construction of a reservoir (NatureServe Network 2021, USFWS 1991, 2011). Extirpated occurrences account for a decrease of 9% in range extent.

The largest population has more than 1,000 plants but most have 200 or fewer plants (USFWS 2011).

Astragalus bibullatus occurs in limestone cedar glade ecosystems in the Middle Tennessee Central Basin. The plants are associated with Lebanon limestone and occur in transitional areas or glade margins where the soils are deeper (5-15 cm) and there is partial shade from shrubs and small trees. Environmental conditions in limestone glades are extreme, being wet in the spring and very dry in the summer.

The foreseeable threat with the greatest impact is limestone glade habitat degradation and loss from development and land clearing. Three occurrences are partially or entirely on privately owned lands (USFWS 2019). Additional significant threats to the species are highway right-of-way maintenance, off-road vehicle traffic, trash dumping, livestock grazing, and encroachment of more competitive herbaceous and woody plants. Active management to reduce competing vegetation is required to ensure the survival of the species, so even brushhogging and mowing by landowners can be beneficial. Collecting could also be a threat (USFWS 1991). Herbivory of the pods has not been observed; seeds appear to be transported by rainfall or mowing/management activities. The seeds probably do not travel far from the original pods before germination.

Eight occurrences are in state designated natural areas. This species is protected under the U.S. Endangered Species Act and listed as 'Endangered'.