| 1 | Accessory branches not always present at ultimate forks. |
| 1' | Accessory branches always present at ultimate forks. |
| 2 | Branches at each fork of a lateral branch-system approximately equal; lateral branch-systems forked 1-3 times. |
| 2' | Branches at successive forks alternately unequal; lateral branch-systems on well-grown plants forked at least 3 times. |
| 3 | Costules less than 5 mm apart, their lower surface with some persistent hairs. |
| 3' | Costules 5-7 mm apart, their lower surface glabrous. |
| 4 | Hairs not persistent on lower surface of veins |
| 4' | Hairs persistent along lower surface of veins. |
| 5 | Hairs long, very finely woolly and entangled; no distinct separate hairs present. |
| 5' | Hairs coarse, shorter, more or less entangled on costules, some distinctly separate on veins. |
| 6 | Lamina thick and rigid |
| 6' | Lamina thin |
| 7 | Lower surface quite glabrous and persistently pale glaucous; lamina thin |
| 7' | Lower surface more or less persistently hairy, less strongly glaucous (often losing glaucous character on drying); lamina firm. |
| 8 | Hairs very slender, their long branches much crisped and entangled; no separate short hairs. |
| 8' | Hairs coarser and shorter, some more or less crisped and entangled but separate short hairs also present. |
| 9 | Hairs copious, at first covering whole lower surface, persistent along the veins, rusty when dry; edges of lamina strongly reflexed when dry |
| 9' | Hairs not covering whole lower surface, persistent only on costules, pale when dry; edges of lamina not much reflexed when dry. |
| 10 | Angle of secondary and later forks not more than a right angle. |
| 10' | Angle of secondary and later forks more than a right angle. |
| 11 | Hairs confined to bases of some of the costules |
| 11' | Hairs more abundant on costules, and some also on veins. |
| 12 | Hairs persistently rust-coloured, copious all along veins. |
| 12' | Hairs pale on dried specimens, sparse on the veins; W. Malaysia. |
| 13 | Accessory branches, especially the lower ones, distinctly below the fork; branches at successive forks alternately somewhat unequal |
| 13' | Accessory branches opposite the fork or distinctly above it; branching usually equal at all forks. |
| 14 | Ratio of length to width of branches commonly 2:1; costules c. 3 mm apart, segments of lamina 2½-3 mm wide |
| 14' | Ratio of length to width greater; costules more widely separated. |
| 15 | Costules on ultimate branches 5-7 mm apart; texture subcoriaceous; lower surface quite glabrous; accessory branches at ultimate forks almost opposite the fork. |
| 15' | Costules on ultimate branches 3½-4½ mm apart; texture thin; some rusty hairs often on lower surface; accessory branches at ultimate forks 3-4 mm above the fork |
