Morton Citrange

Morton Citrange

(X Citroncirus 'Morton')

Documented by Léo — grown in the ground, USDA zone 8b

Morton citrange (× Citroncirus 'Morton') is one of the first Poncirus × orange hybrids ever selected, created by the American USDA program in the early 20th century. Its tree hardiness reaches 5°F (−15°C), among the hardiest edible citrus, making it viable in the ground up to USDA zone 7b. The vigorous tree reaches 10 to 16 ft (3 to 5 m) with an upright, thorny habit, semi-evergreen trifoliate foliage like its Poncirus parent, and white spring flowers. Its yellow-orange fruit, 3.5 to 7 oz (100 to 200 g) with thick skin, ripen in winter and give a markedly sour juice with a sweet-orange aroma, acceptable as juice, in marmalade, or as a cocktail base. A historic reference of the American hardy hybridization program. Graft onto Poncirus trifoliata; it will take continental winters without flinching. Well-drained soil; a south wall is recommended.

Identity

OriginUnited States

Genetic originHybrid Poncirus trifoliata x Citrus sinensis 'Navel'

USDA zone7b

Cold hardiness5°F (−15°C)

Fruit cold hardiness23°F (−5°C)

GrowthModerate

Height16 ft (5 m)

HarvestJanuary, November, December

SeedsModerate

UsesFresh eating, Juice, Preserves

FlavorsSour then sweet, Highly aromatic, Slight bitterness

History & Description

Origin

Morton citrange is an exceptional hybrid from a cross between Poncirus trifoliata (the trifoliate orange, the hardiest of all citrus, resistant down to −13°F (−25°C)) and Citrus sinensis in its Navel form. This selection was made as part of breeding programs in the United States and France aimed at combining the extreme cold resistance of Poncirus with the flavor quality of sweet oranges. The variety is sold in France by specialist nurseries such as the Arche du Livradois, which grows its citrus at an altitude of 3,300 ft (1,000 m) in the Auvergne, and the Jardin Écologique in the Gard. Its exceptional hardiness of 5°F (−15°C) makes it one of the citrus best suited to the harsh winters of the temperate French climate, opening the way to growing it well beyond the Mediterranean basin, in regions reputed to be out of reach for citrus.

Tree description

Tree of moderate vigor, reaching 10 to 16 ft (3 to 5 m) depending on training and the rootstock used. The habit is upright, with dense evergreen foliage. The spring bloom (April to June) is remarkable for the abundance and size of its large, very fragrant white flowers. Fruiting begins gradually, especially on Poncirus rootstock, and is faster on FA5.

Fruit quality

The fruit looks like a small, medium-sized orange, slightly lobed, pale yellow-orange at maturity in late fall and winter. The flesh is juicy but more acidic and slightly bitter than the sweet orange at the start of ripening; it gradually softens when the fruit stays on the tree in winter, then approaching the taste of an orange. The zest is very aromatic. The harvest runs from November to January.

Flavor and ornamental interest

Fully ripe on the tree, Morton citrange can be eaten raw, with a flavor profile approaching that of an orange. It is especially appreciated for jam, marmalade, and juice. Its exceptional hardiness of 5°F (−15°C) places it among the very rare citrus that can be grown in the ground in the continental and mountain regions of France. Its spectacular, fragrant bloom is a major ornamental asset in spring.