| | 1. Leaves generally in bundles of 2–5 (1 in P. monophylla), generally 2.5–35 cm; seed cone bract fused to scale, included, inconspicuous |
| PINUS |
| | 1' Leaves not in bundles, generally 1–6 cm; seed cone bract free from scale, exserted or included, conspicuous |
| |
| | 2. Leaf scar ± flush with twig surface, smooth, round; seed cone erect, scales and bracts deciduous, axis persistent on stem |
| ABIES |
| | 2' Leaf scar raised above twig surface on persistent base, sometimes ± smooth and round; seed cone pendent, the whole ± persistent on stem |
| |
| | 3. Leaf scar ± smooth, round, base not woody, projecting slightly above twig surface; seed cone 4–20 cm, bracts exserted, tip 3-toothed |
| PSEUDOTSUGA |
| | 3' Leaf scar generally not smooth, not round, base woody, projecting conspicuously above twig surface; seed cone 1.2–12 cm, bracts included, entire or fringed |
| |
| | 4. Leaf tip acute or spine-like, persistent base spreading, peg-like; seed cone 5–12 cm |
| PICEA |
| | 4' Leaf tip generally blunt, persistent base ascending, wedge- or scale-like; seed cone 1.2–7.5 cm |
| TSUGA
|