Key for Serjania Miller.

1Cross section of stem with a central vascular cylinder and numerous peripheral vascular cylinders
1'Cross section of stem with a single vascular cylinder
2Cross section of stem with 3 or 5 peripheral, equidistant vascular cylinders
2'Cross section of stem with 8 or 10 peripheral vascular cylinders, arranged in a circular way around the central cylinder
3Stems trigonous, 5-ribbed, glabrous; cross section of stem with 3 (5) peripheral vascular cylinders; leaf rachis usually winged; leaflets with 2-4 rounded teeth just below the obtusely apiculate apex
3'Stems pentagonal, setulose-hispidulose; cross section of stem with 3 peripheral vascular cylinders; leaf rachis margined; leaflets entire or with 2-4 teeth widely spaced along the margins, or less often serrate, the apex acute or acuminate
4Abaxial surface of leaflets strigose, canescent
4'Abaxial surface of leaflet glabrous, puberulent or ferruginous-pubescent, not canescent
5Leaves 5-foliolate pinnate, abaxially glabrous; calyx glabrous or puberulent
5'Leaves biternate, abaxial surface sparsely ferruginous-pubescent; calyx tomentulose
6Plant glabrous
6'Plant pubescent or puberulent
7Leaflets with entire margins; samaras ≥ 3 cm long
7'Leaflets repando-dentate serrate; samaras 2-2.5 cm long
8Plant glandular pubescent or puberulent; leaflets minutely puberulent with sparse, minute, glandular hairs along abaxial surface
8'Plant not glandular pubescent; leaflets sparsely pilose