Shangjuan

Shangjuan

(Citrus wilsonii)

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

Shangjuan (Citrus wilsonii) is a wild Chinese citrus native to the provinces of Yunnan and Guizhou, a cousin of the Ichang lemon, from which it inherits its exceptional tree hardiness of 5°F (−15°C). It can be grown 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, evergreen foliage with the winged petiole characteristic of papedas, and fragrant white spring flowers. Its large yellow fruit, 7.1 to 12.3 oz (200 to 350 g) with thick, rough skin, ripen in winter and give an aromatic, acidic juice reminiscent of a very fragrant grapefruit, with a zest exceptionally rich in essential oils. Used traditionally in Chinese cooking and Tibetan medicine. Its hardiness comes from its wild parent the Ichang papeda, which grows in the cold mountains of southwestern China. Graft onto Poncirus trifoliata.

Identity

OriginChina (Yunnan, Guizhou)

Genetic originWild papeda (close to Citrus cavaleriei)

USDA zone7b

Cold hardiness5°F (−15°C)

Fruit cold hardiness27°F (−3°C)

GrowthModerate

Height16 ft (5 m)

HarvestOctober, November, December

SeedsMany

UsesJuice, Liqueur, Preserves, Savory cooking

FlavorsSour, Highly aromatic, Slight bitterness

History & Description

Origin

Shangjuan, known by the botanical name Citrus wilsonii, is a wild citrus native to central and southern China, in particular the provinces of Yunnan and Guizhou. It belongs to the papeda family, a group of primitive citrus among the closest to the ancestral species, and is among the hardiest citrus known in the world. Cultivated for centuries in high-altitude Chinese mountain regions, it survives where nearly all citrus would perish in winter. Its Chinese name literally means mountain citrus. Ernest Henry Wilson, a British botanist, brought specimens back to the West in the early 20th century, hence its scientific epithet wilsonii. Long considered a mere rootstock or botanical curiosity, it is now grown as a fruit tree in its own right for its exceptional genetic interest and its ornamental qualities.

Tree description

Shangjuan forms a shrubby tree or a small tree that can reach 13 to 16 ft (4 to 5 m), with a bushy, slightly thorny habit. Its dense, glossy dark green evergreen foliage is made up of large elliptical leaves characteristic of papedas. The white, fragrant bloom comes in spring. Growth is moderate and the tree develops a fine natural framework over the years.

Fruit quality

The Shangjuan fruit is imposing, recalling a large grapefruit, 3.1 to 4.7 in (8 to 12 cm) in diameter, yellow-green at fall maturity. The pulp is very acidic and intensely fragrant, with pronounced notes of lemon and grapefruit accompanied by a slight aromatic bitterness. The juice is present but strongly acidic, and the seeds are numerous. The zest is the most valued part for its exceptional aromatic qualities.

Flavor and ornamental interest

Shangjuan finds its main interest in the kitchen thanks to its very aromatic zest, used in jam, in liqueur, or as a condiment in savory dishes in the manner of yuzu. Its extraordinary fragrant profile makes it a sought-after ingredient for creative cooks. Ornamentally, its majestic habit, large white flowers, and imposing fruit make it a remarkable specimen in hardy gardens. Its tolerance of extreme cold, close to that of Poncirus, makes it an ambassador of citrus in the most difficult zones of Europe.