This grass was formerly identified as Polypogon elongatus, native to South and Central America, and the southwest US, but introduced to California, including San Francisco Bay (Cohen and Carlton 1995). However, only two samples were collected, and these have been re-identified as P. imberbis, also native to South America (Jepson and University of California Herbarium 2024; Flora of North America (2024). Currently, this species is regarded as introduced, but not established).