Citron
The citron ("Citrus medica") is a large fragrant citrus fruit with a thick rind. It is one of the original citrus fruits from which all other citrus types developed through natural hybrid speciation or artificial hybridization. Though citron cultivars take on a wide variety of physical forms, they are all closely related genetically. It is used widely in Asian cuisine, and also in traditional medicines, perfume, and for religious rituals and offerings. Hybrids of citrons with other citrus are commercially prominent, notably lemons and many limes.
Bitter orange
Bitter orange, Seville orange, sour orange, bigarade orange, or marmalade orange refers to a citrus tree (Citrus" × "aurantium) and its fruit. It is native to southeast Asia, and has been spread by humans to many parts of the world. Wild trees are found near small streams in generally secluded and wooded parts of Florida and The Bahamas after it was introduced to the area from Spain, where it had been introduced and cultivated heavily beginning in the 10th century by the Moors. The bitter orange is believed to be a cross between "Citrus maxima" × "Citrus reticulata"