| | 1. Leaf needle- or awl-like, sub-erect to spreading but not appressed; pollen, seed cones axillary; shrub < 1 m (sect. Juniperus) |
| J. communis |
| | 1' Leaf generally scale-like, closely appressed; pollen, seed cones terminal; tree or shrub > 1 m (sect. Sabina) |
| |
| | 2. Seed cone maturing blue-black; tree 5–15 m |
| J. occidentalis |
| | 3. Bark red-brown; leaves generally whorled in 3's; generally dioecious; High North Coast Ranges, High Sierra Nevada, San Gabriel Mountains, San Bernardino Mountains, Desert Mountains |
| var. australis |
| | 3' Bark brown; leaves opposite or whorled in 3's; generally ± monoecious; High Cascade Range, Modoc Plateau |
| var. occidentalis |
| | 2' Seed cone maturing red-brown; shrub or tree 1–8(10) m |
| |
| | 4. Leaf gland obvious; trunks several at base; dioecious; mostly California Floristic Province |
| J. californica |
| | 4' Leaf gland obscure; trunk generally 1 at base; monoecious; mostly not California Floristic Province |
| J. osteosperma
|