Moroccan Citron
The Moroccan sweet citron (Hebrew: אִתְרוֹג מֵרוּקָנֶי) was first described in detail by Professor Henri Chapot, in his article named Un curieux cedrat Marocain (1950). He discovered that the acidity in the more common citrons or lemons, is represented by violet pigmentation on the outer side of the flower blossom, and also by the new buds that are reddish-purplish. The Moroccan citron which is acidless is completely lacking the red colour.
This designation was cited by Webber and Batchelor the editors of the fundamental treatise on citrus, namely The Citrus Industry, which was published by the University of California, Riverside in year 1967.
Read more about Moroccan Citron: Use As Etrog, The Lack of Seeds, See Also