Key for Columnea L.

1Leaves of a pair strongly unequal, the larger leaf in a pair ca. 10 times larger than the smaller
1'Leaves of a pair subequal, the larger leaf in a pair at most 4 times larger than the smaller (C. calotricha)
2Leaves with red-purple areas below, sparsely pubescent to pilose above
2'Leaves (in the Guianas) green below, densely tomentose to hirsute above
3Corolla yellow covered with brown or red hairs, subactinomorphic; leaves as long as to much longer than the flowers
3'Corolla scarlet or red, 2-lipped; leaves usually shorter than the flowers
4Pedicels usually as long as the leaves or longer; leaf blade obtuse to acuminate apically, margin entire, subrevolute, glabrous above; calyx lobes sharply serrate, 1.5-3 times longer than wide
4'Pedicels usually much shorter than the leaves; leaf blade acute or obtuse apically, margin entire to remotely crenate-dentate, strigose to subtomentose above; calyx lobe base entire or with a few teeth, 2.5-10 times longer than wide