Willowleaf mandarin is believed to have originated in China, like most mandarins, but it became firmly established and refined around the Mediterranean Basin—particularly in Italy, Spain, and North Africa—by the 19th century. In early European horticultural literature it often appears under names such as Mediterranean mandarin or Common mandarin. Fruit medium in size, moderately oblate, frequently slightly lobed; base sometimes even, but usually with low collared and strongly furrowed neck; apex depressed and commonly slightly wrinkled; areole lacking; small navel-like structure fairly common. Seeds numerous, small, round, plump, and highly polyembryonic, with light green cotyledons. Rind thin, not leathery, loosely adherent; surface smooth and glossy with large, deep colored oil glands; color yellowish-orange at maturity. Segments 10 to 12, very loosely adherent; axis hollow. Flesh color light orange; tender; juicy; flavor sweet; pleasantly aromatic (distinctive). Moderately early to early midseason in maturity. As fruit passes through maturity, rind separation increases sharply and "puffing" takes place, accompanied by marked loss of acidity. Fruit loses quality unless picked promptly. Unfortunately, fruit does not store well (in comparison with satsuma). Tree slow growing, of medium vigor and size, broad-spreading, and drooping in growth habit; branches fine, willowy, and nearly thornless; leaves small, narrowly lanceolate, and of distinctive appearance. Tree hardy to cold and resistant to unfavorable conditions, but exhibits strong tendency to alternate bearing. In comparison with the other mandarins, the most distinctive characteristics of the Mediterranean mandarin include: (1) the small size and narrow-lanceolate form of the leaves and the special nature and aroma of the oil they contain; (2) the mild and pleasantly aromatic flavor of the juice; (3) the distinctive nature and fragrance of the rind oil; and (4) the plump and almost spherical seeds. Additional distinctive characteristics not confined to this mandarin are the spreading-drooping habit of growth and the very high degree of seed polyembryony. After careful review of the literature, Chapot (1962c) has concluded that it appeared in Italy between 1810 and 1818. It is reported to have been imported into Egypt from Malta about 1830 and is known to have been in commercial production in Italy by 1840, whence it was taken to Algeria in 1850. Within a few decades, it spread to all the countries of the Mediterranean basin and Near East and soon attained considerable commercial importance. It was brought to the United States by the Italian consul at New Orleans and planted in the consulate grounds there sometime between 1840 and 1850, apparently being the first mandarin to reach this country. Not long thereafter, it was taken to Florida and thence probably to California and elsewhere. The parentage and mode of origin of this fruit are not known, but it seems likely that it arose as a chance seedling from a mandarin variety or form of Chinese origin. Because of certain resemblances, Tanaka (1954, p. 16) has suggested the possibility that the szu-ui-kom, szinkom, or sun-wui-kom (Citrus suhuiensis Tan.) of southern China might be the seed parent, although he insists that the two species are distinct. As seen by the writer in the collection at the Government Horticultural Research Institute, Saharanpur, India, the latter fruit exhibits numerous and striking similarities to the Mediterranean mandarin, including the habit of growth, appearance, and distinctive flavor and aroma of the fruit. The leaves, however, are much more broadly lanceolate. Because of its high beat requirement, tolerance, and the fact that the fruit is well-shaded, this mandarin is adapted to the hot and dry climates that characterize the Mediterranean basin and Near East. In general, because of the greater amount of heat, both fruit size and quality are superior in North Africa and the season of maturity earlier than in Italy and Spain. The Baladi or Yussef Effendi mandarin of Egypt is notable for earliness of maturity, and size, the latter evidently an effect of the humidity resulting from the flooding of the Nile during summer and early fall. In the heat-deficient coastal region of southern California, the fruit is small, of indifferent quality, and late in maturity.