| 1 | Vessels less than 10 per sq. mm |
| 1' | Vessels over 35 per sq. mm |
| 2 | Ray-vessel pitting of two sizes, small and elongate |
| 2' | Ray-vessel pitting uniform, small |
| 3 | Rays exclusively 1-seriate, procumbent cells absent |
| 3' | Rays partly 2-3-seriate |
| 4 | Fibres septate, thin-walled |
| 4' | Fibres virtually all non-septate, thick-walled |
