Achimenes patens 'Major'

Photo by Leslie Brothers, courtesy of the Smithsonian Institution
Grown at the Smithsonian Institution greenhouses

Note the characteristic "spur" at the base of the flower.  The base of most other Achimenes are enclosed by the calyces, as in this photo of Achimenes longiflora.

Another photo of A. patens illustrates its characteristic attitude and reflexed lobes.