Figure 1. Rabbitfootgrass (Polypogon monspeliensis). This moisture-loving grass probably originated in Europe, but it became a global cosmopolitan so early in human history its origin is uncertain. This one is growing beside the Agua Fria River, a small desert stream in central Arizona. Rabbitfootgrass can spread through dry upland sites by following roadside ditches where it joins a diverse collection of invasive species.