Perhaps most of all Charles was known for his Sinningia speciosa hybrids. They were ever his "Gloxies" and he hybridised and grew a bewildering array of colours and patterns including his wonderful "Rainbow" series of multicoloured flowers. There are a number of "Rainbow" flowers on this page, along with many others.
These are all single flowers, but he also produced many double Sinningia speciosa. Those photographs are on the next page.