| Astragalus chapalanus M.E. Jones, 1923 |
| Astragalus circumdatus Greene, 1888 |
| Astragalus coahuilae M.E. Jones, 1923 |
| Astragalus cobrensis A. Gray, 1853 |
| Astragalus coccineus (Parry) Brandegee, 1891 |
| Astragalus comonduensis A.E. Estrada, Rebman& Villarreal, 2019 |
| Astragalus coriaceus Hemsl., 1879 |
| Astragalus coulteri Benth., 1849 |
| Astragalus crassicarpus Nutt., 1813 |
| Astragalus crescenticarpus E. Sheld., 1894 |
| Astragalus crotalariae A. Gray, 1864 |
| Astragalus crotalariae var. anemophilus (Greene) M.E. Jones, 1902 |
| Astragalus crotalariae var. magdalenae (Greene) M.E. Jones, 1902 |
| Astragalus crotalariae var. piscinus (M.E. Jones) Jeps., 1936 |
| Astragalus daleae Greene, 1888 |
| Astragalus datilensis (Rydb.) Tidestr., 1937 |
| Astragalus davisianus Greene ex Rydb., 1927 |
| Astragalus didymocarpus Hook. & Arn., 1838 |
| Astragalus didymocarpus var. dispermus (A. Gray) Jeps., 1936 |
| Astragalus didymocarpus var. obispensis (Rydb.) Jeps., 1936 |