| | 1. Leaf sheath length ± = width, generally 1–2 mm; petals truncate or shallowly notched |
| P. prolifera |
| | 1' Leaf sheath length 1.5–3 × width, generally 3–9 mm; petals obcordate to 2-lobed |
| |
| | 2. Seeds 1–1.4 mm, conic-papillate; leaf sheath generally 4–9 mm; inner inflorescence bracts like outer, all abruptly pointed |
| P. dubia |
| | 2' Seeds (1.3)1.5–1.8 mm, tubercled; leaf sheath (2)3–4 mm; inner inflorescence bracts obtuse or abruptly pointed |
| P. nanteuilii
|