| | 1. Pistils 4–5(12); styles in fruit 2–6 cm, plumose; leaf lobes (3)5–9, from just below middle |
| P. mexicana var. stansburyana |
| | 1' Pistils 1(–3); styles in fruit < 1 cm, canescent at least below tip; leaf lobes 3(–5), generally from above middle |
| P. tridentata |
| | 2. Leaf upper surface sparsely nonglandular-hairy, sessile or sunken glands few–many; twig hairs mostly glandular |
| var. glandulosa |
| | 2' Leaf upper surface densely nonglandular-hairy, sessile or sunken glands 0–few; twig hairs mostly nonglandular |
| var. tridentata
|