Didymocarpus rexii

Curtis, 1830

This species is now known as Streptocarpus rexii.  The generic name comes from the twisted (strepto) seed pod (carpus), nicely illustrated here.  S. rexii is the principle ancestor of most modern Streptocarpus hybrids.  There are a number of pictures of this variable species on the site.  A white form is similar to the plant in this print, while a lavender form illustrates the long tube which can be seen above.