| | 1. Lower glume < 1/2 upper glume length, sometimes minute |
| V. myuros |
| | 2. Lemma margin ciliate near tip |
| var. hirsuta |
| var. myuros |
| | 1' Lower glume > 1/2 upper glume length |
| |
| | 3. Florets 5–10, closely overlapping; spikelet axis hidden; lemma awn < 4 mm |
| V. octoflora |
| | 4. Lemma back prominently long-scabrous near tip, margins long-scabrous |
| var. hirtella |
| | 4' Lemma back glabrous or barely scabrous, margins often short-scabrous |
| var. octoflora |
| | 3' Florets generally 1–5, loosely overlapping; spikelet axis visible, each internode > 1 mm; lemma awn generally 4–22 mm |
| |
| | 5. Lowest inflorescence branches appressed to erect; branch axil not thickened |
| V. bromoides |
| | 5' Lowest inflorescence branches spreading or reflexed; branch axil thickened |
| V. microstachys |
| | 6. Spikelet glabrous or only scabrous |
| var. pauciflora |
| | 6' Spikelet obviously hairy |
| |
| | 7. Glumes and lemmas hairy |
| var. ciliata |
| | 7' Glumes glabrous and lemma hairy or glumes hairy and lemma glabrous |
| |
| | 8. Glumes hairy; lemma glabrous |
| var. confusa |
| | 8' Glumes glabrous; lemma hairy |
| var. microstachys
|