| | 1. Bud bracts persistent among upper leaves, 15–45 mm, thick, lanceolate; leaflets ± palmately veined |
| B. nervosa |
| | 1' Bud bracts generally deciduous, < 5 mm, thin, ovate to deltate; leaflets generally pinnately veined |
| |
| | 2. Inflorescence open, flowers generally < 10; largest leaflets < 4 cm, < 2 cm wide; petiole < 2 cm; terminal leaflets generally lanceolate, oblong, or narrowly elliptic — Southwestern California, Desert |
| |
| | 3. Leaflets flat to ± wavy, not folded along midrib, margin serrate, teeth generally > 8; spine tips ± 1 mm |
| B. nevinii |
| | 3' Leaflets wavy, generally folded along midrib, margin ± lobed, teeth generally 3–8; spine tips 1–3 mm |
| |
| | 4. Terminal leaflet generally ovate-lanceolate, length generally < 3 × width; flowers 8–12; fruit yellowish red to reddish purple |
| B. fremontii |
| | 4' Terminal leaflet generally narrowly lanceolate, length generally > 3 × width; flowers 3–5; fruit reddish brown to dark purple |
| B. haematocarpa |
| | 2' Inflorescence dense, flowers > 10; largest leaflets generally > 4 cm, > 2 cm wide; petiole generally > 2 cm (0–3 cm in B. pinnata); terminal leaflets generally ovate to widely elliptic |
| |
| | 5. Leaflet margin strongly wavy, thick, generally hard, teeth generally < 10 per margin; spine tips 2–5 mm |
| B. aquifolium var. dictyota |
| | 5' Leaflet margin wavy to flat, ± thin, not hard, teeth generally > 10 per margin; spine tips 1–2 mm |
| |
| | 6. Petioles generally > 3 cm; leaflets generally 5–9 |
| |
| | 7. Stems ascending to erect, generally > 1 m; leaflets generally shiny above |
| B. aquifolium var. aquifolium |
| | 7' Stems spreading, sometimes erect, generally < 1 m; leaflets generally dull above |
| B. aquifolium var. repens |
| | 6' Petioles 0 or < 3 cm; leaflets generally 7–11 |
| B. pinnata |
| | 8. Upper stems reclining or vine-like; plant 2–8 m |
| subsp. insularis |
| | 8' Upper stems erect; plant generally < 2 m |
| subsp. pinnata
|