This is a large-growing species, with branches that can be up to a meter long. Not all specimens have the red-backed leaves (which facilitate attraction of hummingbirds), and some have orange or red calyces and flowers, as here.
The plant featured above was exhibited at the Gesneriad Society’s convention in 2014. Another show plant, from the Gesneriad Society convention in 2009, can be seen here.
A closer view of the stem illustrates the placement of the small and inconspicuous flowers (hence the need for the bright red patches on the leaves to attract pollinators) and the apparent alternate-leaf pattern. The species, like all members of the genus, actually produces leaves in pairs, but one member of each pair does not fully develop.