The clementine is a spontaneous citrus hybrid that arose in the late 19th century in Misserghin, Algeria, in the garden of the orphanage of Brother Marie-Clément Rodier, for whom it would be formally named in 1902. Some sources have attributed an earlier origin for the hybrid, pointing to similar fruit native to the provinces of Guangxi and Guangdong in present-day China, but these are likely distinct mandarin hybrids, and genomic analysis of the clementine has shown it to have arisen from a cross between a sweet orange (Citrus × sinensis) and the Mediterranean willowleaf mandarin (Citrus × deliciosa), consistent with Algerian origin.
There are three types of clementines: seedless clementines, clementines (maximum of 10 seeds), and Monreal (more than 10 seeds). Clementines resemble other citrus varieties such as the satsuma and tangerines.
This variety was introduced into California commercial agriculture in 1914, though it was grown at the Citrus Research Center (now part of the University of California, Riverside) as early as 1909.
Clementines lose their desirable seedless characteristic when they are cross-pollinated with other fruit. In 2006, to prevent this, growers such as Paramount Citrus in California threatened to sue local beekeepers to keep bees away from their crops.
Clementines differ from other citrus in having lower heat requirement, which means the tolerance to fruit maturity and sensitivity to unfavorable conditions during the flowering and fruit-setting period is higher. However, in regions of high total heat, the Clementine bears fruit early; only slightly later than satsuma mandarins. These regions such as North Africa, Mediterranean basin, and California, also favor maximizing the Clementine size and quality. As a result, the tastiest Clementines are from these hot regions.[page needed]
Seedless - exists in North Africa. Seedless versions of the clementine are known as the common type (seedless or practically seedless). Common Clementines are very similar to the Monreal type; the two types are virtually identical in terms of tree specifics. The seedless Clementine tree is self-incompatible; which is why the fruit has so few or no seeds. In order to be pollinated, it needs to be cross-pollinated.[page needed]
Monreal - exists in North Africa. The Monreal clementine can self-pollinate and has seeds. Monreal clementines are on average larger than its seedless variety and has a more abundant bloom and is sweeter.[page needed]
Fina, a Spanish cultivar originally grown on a bitter orange rootstock that gave it superb flavor, but due to disease vulnerability is now grown on a broader range of rootstocks, affecting the flavor profile.
Clemenules or Nules - A popular, seedless, easy to peel clementine with a very pleasing sweet flavor. A mutation of the Fina variety, Nules is the most widely planted clementine in Spain, where it matures from mid-November to mid to late-January. Also widely planted in California, where it matures from October to December. It produces seedless fruit that is larger than the Fina, but less sweet.
In 2016, world production of clementines, mandarin oranges, tangarines and satsumas, reported as a group to FAOSTAT, was 32.8 million tons, led by China with 52% of the global total (table). Producing more than one million tons each in 2016 were Spain, Turkey, Morocco, and Egypt.
^ abShimizu, Tokurou; et al. (2016). "Hybrid Origins of Citrus Varieties Inferred from DNA Marker Analysis of Nuclear and Organelle Genomes". PLOS ONE. 11 (11): e0166969. doi:10.1371/journal.pone.0166969.
^Hicham Benabdelkamel; Leonardo Di Donna; Fabio Mazzotti; Attilio Naccarato; Giovanni Sindona; Antonio Tagarelli; Domenico Taverna (2012). "Authenticity of PGI "Clementine of Calabria" by Multielement Fingerprint". J. Agric. Food Chem. 60 (14): 3717-3726. doi:10.1021/jf2050075.
^Theile, Dirk; Hohmann, Nicolas; Kiemel, Dominik; Gattuso, Giuseppe; Barreca, Davide; Mikus, Gerd; Haefeli, Walter Emil; Schwenger, Vedat; Weiss, Johanna (15 January 2017). "Clementine juice has the potential for drug interactions - In vitro comparison with grapefruit and mandarin juice". European Journal of Pharmaceutical Sciences. 97: 247-256. doi:10.1016/j.ejps.2016.11.021.