Vanhouttea is not actually a genus, it’s a pollination syndrome, and it shares this distinction with species in the genus Paliavana. However, vanhoutteas are bird-pollinated tuberless sinningias, rather than insect- or bat-pollinated tuberless sinningias. Attracting hummingbirds results in similarities in the flowers that are not entirely due to genetic relationships. The corollas are narrow, tubular, and mostly red. Some species have flaring corolla lobes, others don’t.
The species given the name Vanhouttea are scattered over two different genetic groupings in the sinningia alliance, as follows:
Vanhouttea species in the Sinningia group
Vanhouttea species in the Vanhouttea group
A substantive article on the Sinningia Alliance addresses the taxonomy, distribution, and other features of species in the three genera Vanhouttea, Paliavana, and Sinningia.