Citrus Taiwanica (Nansho Daidai)

(Citrus taiwanica Tanaka & Shimada)

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

Citrus taiwanica Nansho-Daidai (Citrus taiwanica Tanaka & Shimada) is the formal botanical classification of the Taiwanese lemon, a plant endemic to Taiwan reported in the Hsinchu and Nanzhuang regions and in the low-elevation forests of the east of the island by the Taiwanese forestry administration. Its hardiness reaches 9°F (−13°C) on the tree, making it suitable for in-ground growing in USDA zones 7b and 8a. The tree reaches 10 to 13 ft (3 to 4 m) with an upright, thorny habit, aromatic evergreen foliage, and highly fragrant white flowers. Its yellow-green fruits at full maturity, medium-sized, with thick, bumpy skin, ripen in winter and hold a very sour, fragrant juice reminiscent of a natural cross between lemon and bitter orange, with unique resinous notes. Traditionally used in Taiwan in cooking, vinegar, marinade, and traditional medicine. Graft onto Poncirus trifoliata, plant against a south wall.

Identity

OriginTaiwan (Nanzhuang Township)

Genetic originTaiwanese species resulting from a natural hybridization between a pummelo and a mandarin, scientifically described in 1926 by Tyozaburo Tanaka and Yaichi Shimada

USDA zone7b

Cold hardiness9°F (−13°C)

Fruit cold hardiness27°F (−3°C)

GrowthVigorous

Height13 ft (4 m)

HarvestJanuary, February, March, December

SeedsMany

UsesLiqueur, Preserves, Savory cooking

FlavorsSour, Pronounced bitterness

History & Description

Origin

Citrus taiwanica, known in Japan as Nansho Daidai (literally "Nanzhuang bitter orange"), is a wild citrus species discovered by the Japanese botanist Yumoto Yataro in Nanzhuang Township in Taiwan. Officially described scientifically in 1926 by Tyozaburo Tanaka and Yaichi Shimada, it is today among the hardiest citrus species ever described. Genetically, it is a natural hybrid between a pummelo and a mandarin, which explains its bitter orange look and its complex aromatic structure. Distributed in France by nurseries specializing in hardy citrus (Pépinière du Bosc, Quissac, Agrumes de Provence), it remains rare in French gardens and is a true botanical witness to the diversity of Asian citrus.

Tree description

The tree is vigorous, reaching 13 ft (4 m) at maturity with an upright, branching, slightly spreading habit. The foliage is evergreen, dark green, and dense, and the tree bears strong thorns on young shoots. The white spring bloom is highly fragrant, followed by abundant fruiting from the fourth year after planting. Hardiness is exceptional: the tree easily withstands 10 to 5°F (−12 to −15°C) in well-drained soil, which places it among the few true Citrus species usable in zone 7b. It is a reference species for understanding the genetics of cold-hardy citrus.

Fruit quality

The fruit is of good size, about 3.5 in (9 cm) in diameter, bright yellow at full maturity, with thick, rough skin and prominent oil glands. The flesh is very sour, marked by a frank bitterness very close to that of the classic bitter orange. Seeds are numerous, which is not surprising for a wild species. The fruit is not edible raw, but its most singular characteristic is its ability to persist on the tree until August without losing its flavor, offering a long picking period spread from December to the end of summer.

Flavor and ornamental interest

In the kitchen, Nansho Daidai is the hardy equivalent of the Mediterranean bitter orange tree: its thick, fragrant zest goes into traditional English marmalades, its sour juice flavors Japanese ponzu and yuzu sauces, and it is used to make original amaro liqueurs. Its dried peel is used in infusions. Ornamentally, it is a spectacular tree: its yellow fruits stay on the branches for nearly eight months, forming a permanent decoration in the winter garden. For the enthusiast, it is a first-rate choice between extreme hardiness and real culinary use of the fruit.