Chinese Cork Oak

Quercus variabilis is native to eastern Asia.

• Found throughout China from Liaoning and Hebei southward to Guangdong, Guangxi, and Yunnan
• Also occurs in Korea (throughout the peninsula) and in Japan (Honshu, Shikoku, and Kyushu)
• Grows at elevations from near sea level to approximately 2,000 meters in western China
• First described by the French botanist Jonas Carlsson Dryander in 1811
• One of the most widely distributed oaks in China, occurring in 22 of China's provinces
• Often a dominant species in deciduous broadleaf forests on mountain slopes and in secondary growth
• The species is closely related to sawtooth oak (Quercus acutissima) and belongs to the section Cerris
• In Korea, it is called "굴참나무" (guljamnamu) and is an important component of lowland and montane forests
• The species has been used in Chinese traditional medicine for centuries

Quercus variabilis is a large deciduous tree with a thick, corky bark and broad crown.

Size:
• Typically 15 to 25 meters tall, occasionally reaching 30 meters
• Trunk diameter: 0.5 to 1.5 meters
• Crown is broad, rounded, and spreading

Bark:
• The most distinctive feature — very thick, corky, grayish-brown bark, reaching 3 to 5 cm or more in thickness
• Deeply fissured into broad, flat ridges
• The cork layer provides excellent fire insulation, allowing the tree to survive surface fires
• Similar in appearance and texture to Mediterranean cork oak bark
• Inner bark is reddish-brown

Leaves:
• Elliptic to oblong-lanceolate, 8 to 18 cm long and 2 to 5 cm wide
• Margins are sharply serrate with bristle-tipped teeth, similar to sawtooth oak
• Dark green above, densely covered with grayish-white stellate hairs beneath — giving a distinctive whitish undersurface
• The dense white hair beneath is a key distinguishing feature from sawtooth oak
• Turn yellowish-brown in autumn

Acorns:
• Ovoid to subglobose, 1.5 to 2.5 cm long
• Cup covers about one-half to two-thirds of the acorn, with long, narrow, reflexed, tomentose scales
• Take two years to mature (biennial)
• Brown at maturity

Chinese cork oak is one of the most important forest trees in eastern Asia.

Habitat:
• Grows on a wide range of sites from moist, fertile valleys to dry, rocky mountain slopes
• Prefers well-drained, acidic to neutral soils
• Extremely drought-tolerant once established
• The thick cork bark provides excellent fire resistance, allowing survival in fire-prone landscapes
• Often a dominant species in secondary forests and reforestation areas in China
• Found in deciduous broadleaf forests alongside other oaks, pines, and various broadleaf species

Ecosystem role:
• Acorns are food for wildlife including wild boar, deer, squirrels, and numerous bird species
• In Korea and Japan, the species supports populations of the endangered mandarin duck, which nests in old tree cavities
• The dense white-haired leaf undersurface creates unique microhabitats for insects and mites
• Important for soil stabilization and erosion control on steep slopes in mountainous terrain
• Widely used in China for reforestation and afforestation programs
• The species supports numerous species of Lepidoptera in its native range
• Dead wood and fallen logs provide habitat for saproxylic organisms