Quercus Linnaeus subgen. Cyclobalanopsis (Oersted) C. K. Schneider.

Trees or rarely shrubs, evergreen. Trunk bark usually smooth, rarely deeply splitting. Winter buds ovoid-globose, ovoid-conical, or rarely ovoid-ellipsoid; scales many, imbricate. Stipules extrapetiolar. Leaves spirally arranged. Male inflorescences pendulous; flowers loosely arranged or clustered on rachis; perianth usually 5- or 6-lobed; stamens as many as perianth lobes, sometimes less, filament slender; pistil rudimentary. Female inflorescences with a solitary flower or spiciform; cupules with 1 flower; perianth 5- or 6-lobed; staminodes sometimes present, small; ovary 3-loculed; styles (2 or)3(or 4); stigmas capitate or dilated. Cupules solitary; bracts scalelike, whorled, connate, in rings or spirally fused. Nut usually 1 per cupule; abortive ovule persisting in subapical, lateral, or basal part of seed. Germination hypogeal.

About 150 species: mainly in tropical and subtropical Asia; 69 species (43 endemic) in China.

Cyclobalanopsis is often treated as a subgenus of Quercus, with all other species of Quercus belonging to subgenus Quercus.

Species of Cyclobalanopsis are among the main components of broad-leaved evergreen forests in China’s southern provinces N to the Qinling Mountains and the Huai He basin. In general, Cyclobalanopsis has a more southern distribution and Quercus a more northern distribution.