CITRON, a species of Citrus (C. medica), belonging to the tribe Aurantieae of the rue family (Rutaceae) ; the same genus furnishes also the orange, lemon, lime and shaddock or grapefruit. The citron is a small, evergreen tree or shrub growing to a height of about i o ft.; it has irregular, straggling, spiny branches, large pale green, broadly oblong, slightly serrate leaves, with wingless petioles, and generally unisexual flowers, purplish without and white within. The large fruit is ovate or oblong, protuberant at the tip, and from 5 in. to 6 in. long, with a rough, furrowed, ad hesive rind, the inner portion of which is thick, white and fleshy, the outer, thin, greenish-yellow and very fragrant. The pulp is very acid and inedible, and the seeds are bitter; the peel is very thick and when candied of very agreeable flavour. There are many varieties of the fruit, some of them of great weight and size, but only one variety, the so-called Corsican citron, is grown on an extensive commercial scale. Its large fruits are used for making candied citron, highly esteemed as a confection, of which large quantities, from 2,500,000 lb. to 4,500,000 lb. annually, are consumed in the United States. Recent researches show that the citron peel must go through a fermentation in sea water to pre pare it for being candied.
The citron-tree thrives in the open air in China, Persia, the West Indies, Madeira, Sicily, Corsica, and the warmer parts of Spain and Italy ; and in. conservatories in more northerly regions. The rind of the citron yields a fragrant essential oil called oil of citron but it is seldom collected. Other varieties of Citrus medica yield oils known as oil of cedro and oil of cedrino.
See J. A. Risso and A. Poiteau, Histoire naturelle des orangers (1818 19, 2nd ed., 1872) ; E. Bonavia, The Cultivated Oranges and Lemons, etc., of India and Ceylon (189o) ; J. B. McNair, "Citrus Products," Parts I. and II., Field Museum of Natural History Botanical Series, vol. vi., nos. I and 2 (1926, 1927) ; Lucia McCulloch "Curing and Preserving Citron," Circular no. 13, U.S. Dept. of Agric. (1927).