But I'm here to say a word about Streptocarpus kentaniensis, a species from South Africa. It is said to be quite a dry grower (and therefore good for underwaterers) and floriferous (although each flower is small). The characteristic narrow leaves and flower count can be seen in many hybrids made from this species.
A dry grower sounds like a good candidate for me, but.... If you try this (as I first did) on a light shelf in a room that has a steady temperature (night and day, year-round), and water it on a flood/drought cycle (as I am like to do), then it will not bloom much at all, or even grow all that much. (You shouldn't be surprised, really, as not many houseplants would like to live like that.) I've found it's not a "dry grower" but rather that it dislikes being wet. It has been much happier in a very porous mix with a mostly-steady supply of water, a feat I managed by placing it on my way to the coffee pot where it benefited from a daily water-check. Now I have one on a wick connected to a reservoir that dries out occasionally.
As for the flowering, it only blooms for me on a windowsill: when the night temperatures started dropping and the windowsill got quite, quite cold, Streptocarpus kentaniensis decided it liked this much better and sent up a nice mass of flowers. Here it is, with more flower spikes on the way:
It's certainly not a show-worthy specimen - you can see the trimmed-off leaf tips and other signs of stress thanks to a summer of neglect. Its parent looked much better growing on my coffee route. But flowers? This one has flowers.