Citrofortunella are a large group of commercial hybrids that cross the kumquat with other citrus. In the system of citrus taxonomy established by Swingle, kumquats were placed in a different genus, Fortunella, from Citrus, which included citron, mandarin orange, pomelo and papedas. The result of genetic crosses between kumquats and these other citrus would then be intergeneric hybrids, so a novel genus name was coined for them in 1975, by compounding the names of the contributing genera to form Citrofortunella. That the genus is of a hybrid nature is represented by a multiplication sign before the genus name, for example × Citrofortunella microcarpa. Recent phylogenetic work has shown kumquats to fall within Citrus rather than belonging to a distinct genus, meaning these would no longer be considered intergeneric hybrids, and use of Citrofortunella as a distinct genus name for these hybrids loses taxonomic validity. All would be placed instead within Citrus.