1. Leaves basal, petiolate, usually minutely brown punctate .

2. Leaves alternate, simple, shortly or long petiolate, not stipulate.

3. Leaves opposite or alternate, petiolate , margin entire.

3.

4. Leaves alternate, usually simple, petiolate; leaf blade margin entire or sometimes crenate.

5. Leaves sessile or shortly petiolate , petiole to 5 mm; perianth tube not pubescent inside.

6. Leaves alternate, petiolate ; leaf blade ovate to linear, margin entire or nearly so.

7. Leaves alternate, petiolate, thinly leathery or papery, margin dentate in apical half , rarely entire, lateral veins 2 or 3 pairs, lowest triplinerved.

8. Trees or shrubs. Leaves petiolate , entire or serrate at margin.

9. Leaves 4 to many, very rarely 3, in a terminal whorl , petiolate, lanceolate to ovate, with 3 main veins and anastomosing veinlets.

10. At the end , The paper analyzed the primary factor of petiolate rate.