| 1 | Nerves curving round towards the margin and anastomosing to form a distinct intramarginal nerve. |
| 1' | Not as above. |
| 2 | Bark surface irregular section fissured, flaking but not scroll-marked; inner bark distinctly tangentially laminated. Leaf tertiary nerves scalariform, well spaced, distinct; main nerves ± prominent; petiole swollen at base of lamina, geniculate. Leaf undersurface densely lepidote 2. Anisoptera |
| 2' | Bark surface at first smooth, becoming scaly and distinctly scroll-marked, inner bark homogeneous pale brown. Leaf tertiary nerves indistinct; main nerves slender, hardly raised, petiole not swollen at base of lamina, not geniculate. Leaf undersurface lepidote |
| 3 | Fresh leaves on crushing and cut wood +- aromatic; leaf nervation parallel, nerves equal 6. Dryobalanops |
| 3' | Fresh leaves on crushing and cut wood smelling resinous, but not aromatic; nervation not as above. |
| 4 | Bark surface, if smooth, chocolate and grey dappled and with thin buttresses; or, if pale brown, wood not dense, ray ends glistening on tangential surface; leaf tertiary nerves scalariform, or, if reticulate, drying black. |
| 4' | Buttresses low, rounded; bark surface smooth, pale grey-brown; innner bark homogeneous cream to pale brown; wood close textured, ray ends not glistening on tangential surface; leaf tertiary nerves generally reticulate, not drying black |
| 5 | Leaf nervation dryobalanoid or subdryobalanoid. Fig. 64b-c many |
| 5' | Leaf nervation not as above Neobalanocarpus, some Hopea, Shorea (For distinction between these and their sections, see other keys.) |
| 6 | Bark with large pale warty lenticels more or less densely dotted over the surface, or arranged in groups, more rarely in lines; leaf nerves straight, curving round only near the margin, usually distinctly undulate between each nerve owing to the slight persistence of the plicate folding in bud. |
| 6' | Lenticels small, usually inconspicuous; leaf nerves +- curved from their bases; leaf not folded, vernation not plicate. |
| 7 | Bark surface yellowish to orange-brown or rust, rarely pink-brown, more or less smooth or flaky; terminal leaf buds prominent, stipule scars amplexicaul; petiole distinctly swollen at base of leaf; leaf coriaceous, not lepidote |
| 7' | Bark surface mauve-brown to dark purplish brown or tawny brown; more or less closely shallowly fissured, later flaking in small oblong pieces; petiole not or hardly swollen at base of leaf; terminal buds usually small (excl. P. macrophylla); stipule scars short (excl. P. macrophylla, P. malaanonan); leaf thin, white-lepidote beneath at least in saplings and seedlings, frequently so in mature trees |
| 8 | Base cordate; leathery leaf undersurface with a dense felt of white hairs, with darker, pale brown, nervation; bark surface dark chocolate-brown, closely fissured and flaking; buttress low, rounded |
| 8' | Leaf not cordate at base, or, if cordate, without white tomentose undersurface. |
