The citrange (a portmanteau of citrus and orange) is a citrus hybrid of the sweet orange and the trifoliate orange.
The purpose of this cross was to attempt to create a cold hardy citrus tree (which is the nature of a trifoliate), with delicious fruit like those of the sweet orange. However, citranges are generally bitter.
Citrange is used as a rootstock for citrus in Morocco, but does not prevent dry root rot or exocortis disease.[1]
There are several named citrange cultivars, including the 'Carrizo' citrange and the 'Troyer' citrange. Both resulted from a hybrid between the trifoliate orange and the Washington navel orange. There is also a cultivar called 'Rusk' which resulted from a cross between a Ruby orange and a trifoliate orange.[2]