| | 1. Inflorescence a raceme, flowers 10–many; fruits on naked inflorescence axis |
| |
| | 2. Raceme short, flat-topped; flowers 3–12 |
| 2 P. emarginata |
| | 2' Raceme longer than wide; flowers generally 15–many |
| |
| | 3. Pedicel 5–8 mm; petals 4–7 mm; fruit 6–14 mm, pulp thick; leaf margin finely serrate; leaves deciduous |
| P. virginiana var. demissa |
| | 3' Pedicel 1–5 mm; petals 1–3 mm; fruit 12–22 mm, pulp thin; leaf margin entire or spiny-serrate; leaves evergreen |
| P. ilicifolia |
| | 4. Leaf margin spiny-serrate, ± wavy, blade widely ovate to round; petiole 4–10 mm; mainland |
| subsp. ilicifolia |
| | 4' Leaf margin generally entire, flat, blade generally ovate; petiole 10–25 mm; Channel Islands |
| subsp. lyonii |
| | 1' Inflorescence a cluster, often umbel-like, flowers 1–12; fruits from short, leafy branchlet or leaf axil |
| |
| | 5. Twigs flexible to ± stiff, generally not becoming spine-like; ovary and fruit generally glabrous (except P. dulcis) <|,"61"> |
| |
| | 6. Flowers subsessile, pedicel in fruit generally < 3 mm; sepal back glabrous, margin tomentose; fruit densely puberulent, gray-green, pulp leathery |
| P. dulcis |
| | 6' Pedicel 3–15 mm; sepals glabrous to evenly puberulent; fruit generally glabrous, yellow to purple |
| |
| | 7. Pedicel 3–12 mm; inflorescence raceme-like; fruit 7–14 mm; some or all leaf blades widest above middle |
| 2 P. emarginata |
| | 7' Pedicel 10–15 mm; inflorescence umbel-like; fruit 15–30 mm; some or all leaf blades widest at or below middle |
| |
| | 8. Petiole 15–20 mm; leaf blade 45–80 mm; generally tree near human habitation |
| P. cerasifera |
| | 8' Petiole 4–15 mm; leaf blade 25–50 mm; generally shrub, native |
| P. subcordata |
| | 5' Twigs rigid, generally becoming spine-like; ovary and fruit generally densely puberulent |
| |
| | 9. Leaf blade ovate to round, 7–22 mm wide, base obtuse to ± cordate |
| P. fremontii |
| | 9' Leaf blade narrowly elliptic to oblanceolate, 1–7 mm wide, base tapered |
| |
| | 10. Petals reddish, 5–9 mm; leaf blade 4–7 mm wide, finely serrate |
| P. andersonii |
| | 10' Petals white to yellowish, 2–4 mm; leaf blade 1–3 mm wide, generally entire |
| P. fasciculata |
| | 11. Leaf surface puberulent; inland |
| var. fasciculata |
| | 11' Leaf surface glabrous to low-papillate; coastal |
| var. punctata
|