| 1 | Indumentum on the undersurface of young leaves giving a woolly appearance to the naked eye, and under a lens representing two distinct strata, i.e. an upper layer of partly flattish, though mostly obliquely erect star-shaped or fascicled hairs (with a very small or generally invisible dark centre), and a lower layer of scales. |
| 1' | Indumentum on the undersurface of young leaves giving a scaly appearance to the naked eye, seemingly representing a single layer of scales, but under the lens appearing to consist of two layers of flat star-shaped scales, i.e. a lower layer of ± persistent, small and densely arranged scales, and an upper layer of similar, though larger and more scattered, rather early caducous ones. |
| 2 | Leaves shortly cordate at base, almost peltate, lateral nerves, veins and veinlets ± distinctly impressed above, the lamina ± bullate, hairs persistent. |
| 2' | Leaves never properly cordate at base, nerves sometimes, veins and veinlets never impressed above, hairs generally early disappearing except along midrib and nerves. |
| 3 | Leaves (elliptic or ovate-elliptic, rarely ovate) coriaceous, rigid. |
| 3' | Leaves (of various shape) coriaceous to subcoriaceous, ± flexible. |
