| | 1. Upper leaf blades abruptly spreading to reflexed; mature spikelets generally spreading |
| D. californica |
| | 2. Leaves, especially sheaths, densely hairy, hairs papillate at base; florets generally 3–5 |
| var. americana |
| | 2' Leaves generally glabrous, hairy near ligule but not papillate; florets generally 4–8 |
| var. californica |
| | 1' Upper leaf blades erect to appressed; mature spikelets ascending to erect |
| |
| | 3. Leaves generally glabrous, not papillate |
| D. intermedia |
| | 3' Leaves generally densely hairy, hairs papillate at base or papillate without hairs |
| |
| | 4. Spikelets 6–18 per inflorescence |
| D. pilosa |
| | 4' Spikelets 1–4 per inflorescence |
| D. unispicata
|