This annual occurs mostly in dry sandy prairies of south-central states, and it appears to be adventive in the southeast (W). The only Ky. records are two colls. of R. Athey in the 1970s (EKY, MEM, NCU), from FULT and MCRA (Browne & Athey 1976). In damper areas, two southeastern species in this genus may also be expected: S. divaricata (Walt.) Raf. ex Seringe, especially on sandy soils; and S. inermis (Nutt. ex DC) Mathias & Constance, especially on calcareous soils.