Key for Cupania L.

1Leaves with only two leaflets (sometimes up to 4 in C. diphylla in same plant); leaflets with entire margins
1'Leaves with > than 4 leaflets; leaflets with serrate or crenate margins
2Leaflets obovate or elliptic, abaxially ferruginous-tomentulose, especially along the prominent veins; tertiary veins prominent, subclathrate; margins slightly revolute
2'Leaflets elliptic or oblong-elliptic, abaxially glabrous except for the puberulent midvein; tertiary veins non-prominent, reticulate; margins strongly revolute
3Leaflets abaxially puberulous or glabrous
3'Leaflets abaxially hirsute or hispid
4Leaflets with pit domatia on secondary vein axils, tertiary veins reticulate; margins remotely serrate, entire, subentire, repando-dentate, and undulate; apex acute or shortly acuminate, or sometimes rounded and retuse
4'Leaflets lacking pit domatia on secondary vein axils, tertiary veins subclathrate; margins slightly crenate; apex acuminate, caudate, obtusely acuminate, or sometimes obtuse and retuse
5Leaflets obovate to oblanceolate, retuse at apex; capsule trigonous-depressed-globose
5'Leaflets elliptic, oblong, or oblanceolate, acute, acuminate, apiculate, or sometimes obtuse or minutely retuse at apex; capsule deeply trilobate or tricoccate
6Plant hirsute; leaflets chartaceous or sometimes subcoriaceous, the blade flat, with acute, acuminate or apiculate apex, margins straight or slightly revolute, abaxial surface hirsute along the prominent network of veins; capsules hirsute
6'Plant tomentose; leaflets coriaceous, the blade conduplicate, with obtuse or slightly retuse apex, margins revolute or strongly revolute, abaxial surface hirtellous; capsules sericeous-tomentose