I. Spikelets one-flowered.
| i. | Empty glumes 4. | 5. Phalarideae. |
| ii. | Empty glumes 2. | 6. Agrostideae. |
II. Spikelets more than one-flowered.
i. Fertile glumes generally shorter than the empty glumes, usually with a bent awn on the back.
7. Aveneae.
ii. Fertile glumes generally longer than the empty, unawned or with a straight, terminal awn.
9. Festuceae.
β Spikelets crowded in two close rows, forming a one-sided spike or raceme with a continuous (not jointed) rachis.
8. Chlorideae.
γ Spikelets in two opposite rows forming an equal-sided spike.