| | 1. Young shoots in flat clusters; seeds 2–5 per scale, wing prominent; seed cone 6–12 mm, opening in 1–2 years (subg. Chamaecyparis) |
| |
| | 2. Bark 15–25 cm thick, fibrous; seed cone scales generally 7–10; leaf glands generally visible; leaf generally glaucous |
| C. lawsoniana |
| | 2' Bark 1–2 cm thick, scaly; seed cone scales generally 4–6; leaf glands generally obscure; leaf not glaucous |
| C. nootkatensis |
| | 1' Young shoots generally in 3-dimensional clusters (except sometimes C. macnabiana); seeds > 5 per scale, wing ± obscure; seed cone 10–50 mm, opening in 2 or more years or generally closed indefinitely (subg. Cupressus) |
| |
| | 3. Outer leaf surface generally with conspicuous gland or pit, generally covered with resin that dries clear to white to gray; leaf dull to gray-green, often appearing bluish gray |
| |
| | 4. Young shoots in flat clusters; leaf pungent-scented; resin copious, sticky when fresh |
| C. macnabiana |
| | 4' Young shoots in 3-dimensional clusters; leaf light-scented; resin neither copious nor sticky |
| |
| | 5. Youngest shoots 0.5–1 mm diam; pollen cone 2–3 mm, scales 6–10; seed 3–4 mm; n California |
| C. bakeri |
| | 5' Youngest shoots 1–2 mm diam; pollen cone (2)3–5 mm, scales 8–16; seed (3)4–8 mm; s California |
| C. arizonica |
| | 6. Bark smooth, peeling in thin strips or plates; seed cone scale projection 2–4 mm; leaf glands generally inactive, sometimes inconspicuous or 0; Peninsular Ranges |
| subsp. arizonica |
| | 6' Bark fibrous, not peeling; seed cone scale projection ± 0; leaf glands active, conspicuous; s High Sierra Nevada |
| subsp. nevadensis |
| | 3' Outer leaf surface without conspicuous gland or pit, generally not covered with resin (see also 6. above; C. sargentii has resin, some glands or pits); leaf bright green to dusty green, not grayish |
| |
| | 7. Bark of large branches and trunks cherry-red to mahogany-brown, smooth, polished, not fibrous, peeling in thin plates; small tree generally without dominant terminal shoot; s California |
| C. forbesii |
| | 7' Bark of large branches and trunks not cherry-red to mahogany-brown, generally fibrous, not peeling in thin plates; small to large tree with dominant terminal shoot; n&c California |
| |
| | 8. Leaf dull, dusty green, glaucous or not; serpentine; North Coast Ranges, San Francisco Bay Area, South Coast Ranges |
| C. sargentii |
| | 8' Leaf bright or dark green, not glaucous; not on serpentine; North Coast, Central Coast, San Francisco Bay Area |
| |
| | 9. Crown asymmetric, often open, flat-topped to widely conic; young shoots 1.5–2.5 mm diam; widely planted and naturalized |
| C. macrocarpa |
| | 9' Crown symmetric, often dense, generally pyramidal; young shoots 1–1.5 mm diam; not widely planted and naturalized |
| |
| | 10. Seed 3–5 mm, brown, glaucous or not, attachment scar conspicuous; seed cone generally 15–30 mm, spheric to generally widely cylindric; San Francisco Bay Area (Santa Cruz Mtns) |
| C. abramsiana |
| | 10' Seed 2–4 mm, dark brown to black, not glaucous, attachment scar often inconspicuous; seed cone 10–20(25) mm, ± spheric; North Coast, Central Coast |
| C. goveniana |
| | 11. Tree 5–7 m, terminal shoot not long and whip-like; leaf light to yellow-green; Central Coast |
| subsp. goveniana |
| | 11' Tree 1–2 m on sterile soil (10–50 m on rich soil), terminal shoot long, whip-like; leaf generally dark dull green; North Coast |
| subsp. pigmaea
|