| 1. Spikelet nearly round, obtuse; style 3-branched |
| F. miliacea |
| 1' Spikelet elongate, acute; style 2-branched |
| |
| 2. Peduncles generally long; flower bracts densely hairy; perennial herb |
| F. thermalis |
| 2' Spikelet subsessile; flower bracts glabrous; annual |
| F. vahlii
|