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Morton, J. 1987. Tangelo. p. 158–160. In: Fruits of warm climates. Julia F. Morton, Miami, FL.


Citrus paradisi × Citrus reticulata

Tangelos; are deliberate or accidental hybrids of any mandarin orange and the grapefruit or pummelo. The first known crosses were made by Dr. Walter T. Swingle at Eustis, Florida, in 1897, and Dr. Herbert J. Webber at Riverside, California, in 1898. They are so unlike other citrus fruits that they have been set aside in a class by themselves designated Citrus X tangelo J. Ingram & H. E. Moore (C. X paradisi X C. reticulata).

Tangelos range from the size of a standard sweet orange to the size of a grapefruit, but are usually somewhat necked at the base. The peel is fairly loose and easily removed. The pulp is often colorful, subacid, of fine flavor and very juicy. The trees are large, more cold-tolerant than the grapefruit but not quite as hardy as the mandarin. Nucellar embryos are not uncommon in these hybrids and most of the cultivars are self-sterile, so a majority come true from seed. Tangelos are not commonly grown in California but are produced commercially and in home gardens in Florida. They are much more satisfactory on limestone in southern Florida than the sweet orange and are prized for their quality.

Among the better-known tangelo cultivars are:

Plate XIX: TANGELO, Citrus × tangelo
'K–Early' ('Sunrise Tangelo')–a hybrid propagated by growers. It is an early-maturing cultivar of such poor quality that it gave tangelos a bad reputation. The Official Rules Affecting the Florida Citrus Industry require that it be sold only as 'K-Early Citrus Fruit'.

'Minneola'–a hybrid of 'Bowen' grapefruit and 'Dancy' tangerine; oblate, faintly necked; medium-large, 3 1/4 in (8.25 cm) wide, 3 in (7.5 cm) high; peel deep red-orange, thin, firm, not loose; pulp orange, with 10-12 segments, melting, sweet-acid; of fine flavor; 7-12 small seeds, green inside. Late in season. Ships well. If crop is left too long on tree, the next crop will be light. Bears better if honeybees are provided and if 'Temple' tangor is interplanted as a pollenizer, but the 'Temple' is not as cold-hardy as the 'Minneola', and the trees tend to crowd each other. The 'Minneola' needs fertile soil, irrigation and adequate nutrition. Effects to increase production of seedless fruits include spraying the blooms with gibberellic acid, or girdling during full bloom. The former reduces fruit size and the latter may induce virus outbreaks causing scaling and flaking of the bark.

'Nova'–a 'Clementine' tangerine and 'Orlando' tangelo cross made by Dr. Jack Bellows in 1942, first fruited in 1950, and released by the United States Department of Agriculture's Horticultural Field Station, Orlando, Florida, in 1964. Fruit is oblate to rounded, of medium size, 2 3/4-3 in (7-7.5 cm) wide, 2 1/2-2 3/4 in (6.25-7 cm) high; peel is orange to scarlet, thin, slightly rough, leathery, easy to remove; pulp dark-orange, with about 11 segments, of good, sweet flavor; seeds numerous if cross-pollinated; polyembryonic, green inside. Early in season (mid-September to mid-December). Does very well on 'Cleopatra' rootstock. The tree resembles that of the 'Clementine' tangerine, its twigs are thornless, and it is more cold-hardy than 'Orlando'. This cultivar is self-infertile and trials have shown that 'Temple' tangor is a good pollenizer.

'Orlando' (formerly Take')–result of 'Bowen' grapefruit pollinated with 'Dancy' tangerine, by Dr. Swingle in 1911. The fruit is oblate to rounded, of medium size, 3 in (7.5 cm) wide, 2 3/4 in (7 cm) high; peel deep-orange, slightly rough, not loose; pulp deep-orange, with 12 to 14 segments, melting, very juicy, sweet; seeds 10-12. Early in season but after 'Nova'. A good commercial fruit in Florida. Needs cross-pollination by 'Temple' tangor, or by 'Dancy' or 'Fairchild' tangerines. The presence of honeybees, even without interplanting with a pollinator tree, has greatly increased yields. 'Cleopatra' mandarin is often used as a rootstock on sandy soils, but higher yields have been obtained on sweet lime and rough lemon in Florida. In Texas, 'Orlando' is most productive on 'Swingle citrumelo', 'Morton citrange', 'Rangpur lime' and 'Cleopatra' mandarin. Fruit quality is best on 'Morton citrange', sour orange, 'Sun Cha Sha Kat', 'Keraji' and 'Kinokune' mandarins.

'Seminole'–a hybrid of 'Bowen' grapefruit and 'Dancy' tangerine; oblate, not necked; medium-large, 3 1/4 in (8.25 cm) wide, 2 3/4 in (7 cm) high; peel deep red-orange, thin, firm, almost tight but not hard to remove; pulp deep-orange with 11-13 segments, little rag, melting, of fine, subacid flavor; seeds small, 20-25, green inside. Early in season but holds well through March. Tree vigorous and high-yielding, scab-resistant; leaves with faint or no wings, tangerine-scented.

'Thornton'–a tangerine-grapefruit hybrid created by Dr. Swingle in 1899; oblate to obovate, a little rough and lumpy, puffy with age; medium-large, 3 1/4 -3 3/4 in (8.25-9.5 cm) wide, 2 7/8-3 1/4 in (7.25-8.25 cm) high; peel, light-orange, medium-thick, almost loose, easily removed; pulp pale- to deep-orange, with 10-12 segments, soft, melting, juicy, of rich subacid to sweet flavor; seeds slender, 10-25, green inside. Matures from December to March. Tree vigorous and high-yielding, large-leaved, well adapted to hot, dry regions of California. Fruit is a poor shipper.

The 'Ugli' tangelo of Jamaica
Fig. 40: The 'Ugli' tangelo of Jamaica is believed to be a chance hybrid between a Mandarin orange and a grapefruit.

'Ugli'–believed to be a chance hybrid between a mandarin orange and grapefruit. The discoverer, G. G. R. Sharp, owner of Trout Hall Estate, Jamaica, reported that it was found growing in a pasture around 1917. He took budwood and grafted onto sour orange, and kept on regrafting the progeny with the fewest seeds. Sharp was exporting to England and Canada in 1934 and to markets in New York City in 1942. The fruit is obovoid, compressed to nearly oblate, necked at the base, puffy; large, 4 1/4 to 6 in (10.8-15 cm) wide, 3 1/4-4 1/2 in (8.25-11.5 cm) high; peel is light-yellow with light-green areas at apex, leathery, loose, medium-thin; albedo is thick; pulp light-orange, or apricot, divided into 12 segments with tough membranes, easily skinned; tender, melting, very juicy; of fine flavor, superior to grapefruit, only faintly bitter; seedless or with 3 or a few more medium-sized seeds, white inside. In Jamaica, matures in December and January.

In January 1942, Kendal Morton purchased fruits on the New York market, sent 2 to Dr. H. Harold Hume of the University of Florida, and 4 to Dr. H J. Webber of the University of California, Riverside. Dr. Webber was able to examine them only at the Quarantine Station but he wrote up the description for the first edition of the book, The Citrus Industry, by Batchelor and Webber. He planted the seeds and reported that, of 13 seedlings, 6 had strongly mandarin-scented leaves, 3 had weak-mandarin scent, and 4 had leaf-scent reminiscent of grapefruit or sweet orange leaves. Dr. Webber passed on in 1943 before he could carry out his plans to bud 2 trees from each seedling. Dr. W. P. Betters, Associate Horticulturist, reported that in 1947 the 4 seedlings still in the nursery were bearing fruit, mostly in May-June; the fruits averaged 6 in (15 cm) in diameter, the peel was orange-yellow with a slight tendency to regreen in the spring, the albedo was very thick and fibrous, the flavor of the orange, juicy pulp was good but with a grapefruit tang, and there was, on the average, one seed in each segment. These trees were destroyed in 1951 because they were in the path of campus development, but budwood was taken for propagation and the new trees were beginning to bear in 1954. The 'Ugli' was considered a good fruit for home dooryards in California and was being tried as a rootstock for lemon. The 'Ugli' is little known in Florida. James McClure of Lake Placid has a few trees that bear in February. There are small groves of 'Ugli' in South Africa. In New Zealand a similar fruit has been grown since 1861 as "Poor-man's orange", or "Poorman grapefruit".

'Alamoen'–a fruit rather like the 'Ugli' commonly grown from seeds in Surinam. J.B. Rorer, a Plant Pathologist in Trinidad, saw it in Surinam, considered it better-flavored than the grapefruit, and sent 3 specimens to Dr. David Fairchild in 1914. Under the introduction number 37804, seeds were planted at the United States Department of Agriculture's Garden at Chico, California. Fruits borne by the seedlings had very thick peel and very little juice. Two of the trees were sent to Dr. Fairchild and he planted them at his home, The Kampong, in Coconut Grove, Miami. They began fruiting in 1931 and the fruits were not equal in quality to those he had received from Surinam, which were much lighter in weight because of large, hollow centers. In 1944, he sent fruits to Dr. Webber who detected several points of similarity to the 'Ugli' but found the latter easier to peel and superior in quality and flavor.