Louis Trabut described the Clementine as a naturally occurring citrus hybrid, inferred to have arisen from a cross between a mandarin (tangerine) and a sour orange (bigarade) type, most likely the cultivar known as Granito. This conclusion was based on orchard context and the fruit’s intermediate characteristics, rather than controlled pollination. The Clementine was first introduced to the United States in 1909, when budwood was sent by Trabut—then chief of the Botanical Service of Algeria—to Walter T. Swingle. Swingle propagated and evaluated the variety at Glen St. Mary, Florida, from which it entered broader cultivation and later breeding programs. Trabut noted that the tree is vigorous and productive, with a growth habit similar to a mandarin but often stronger in development. The fruit is mandarin-sized to slightly flattened, with a thin, smooth, orange-red rind, juicy flesh, and a pleasant, sweet flavor with low acidity. It was distinguished from other mandarins of the time by its early maturity, fine texture, aromatic quality, and relatively low seed count, making it especially suitable for fresh consumption. Mentioned in The Citrus Industry Volume 1 (1967) when referring to the Willowleaf/Mediterranean mandarin is "According to Trabut (1902a, 1902b), the Clementine mandarin, now replacing the Mediterranean mandarin in parts of North Africa, is probably a natural hybrid of it and the Granito bitter orange, a view which has never received complete acceptance and seems highly doubtful. However, this fruit is the pollen parent of three hybrid varieties currently of any interest in California and elsewhere—Encore, Kinnow, and Wilking—created by Frost (1935). The seed parent of the hybrids is King mandarin."