| | 1. Margins of upper glume and lower floret lemma glabrous |
| |
| | 2. Upper glume puberulent on back; leaves clearly 2-ranked |
| P. distichum |
| | 2' Upper glume glabrous on back; leaves not clearly 2-ranked |
| P. notatum |
| | 1' Margins of upper glume and lower floret lemma ciliate |
| |
| | 3. Main inflorescence axis with 3–6 branches; spikelet ± 3–4 mm |
| P. dilatatum |
| | 3' Main inflorescence axis with 12–20 branches; spikelet ± 1.5–3 mm |
| P. urvillei
|