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.
Citrus
The Moroccan professor Henri Chapot discovered that the acidity in the more common citrons or lemons is indicated by red on the inner coat of seeds specifically on the chalazal spot, violet pigmentation on the outer side of the flower blossom, and by the new buds that are reddish-purplish. The acid-free varieties of citrus are completely lacking the red color in all the mentioned spots. This designation was cited by Herbert John Webber and Leon Dexter Batchelor, the editors of the fundamental treatise on citrus, namely The Citrus Industry, which was published by the University of California, Riverside in 1967.