Castanopsis, commonly called chinquapin or chinkapin, is a genus of evergreen trees belonging to the beech family, Fagaceae. The genus contains about 120 species, which are today restricted to tropical and subtropical eastern Asia. A total of 58 species are native to China, with 30 endemic; the other species occur further south, through Indochina to Indonesia, and also in Japan. The English name chinkapin is shared with other related plants, including the golden chinkapins of the Pacific United States, which are sometimes included within Castanopsis but are more often considered a separate but very closely related genus, Chrysolepis.
They show many characters typical of Fagaceae. They are at least large shrubs but some species grow into sizeable trees. Their leaves are usually tough and much sclerotized and have a well-developed cuticula. Their flowers are unisexual, and the male ones are borne in erect catkins. The epigynous female flowers produce a single seed each but are congregated in small clusters. The fruit is a calybium, the kind of encased nut typical of Fagaceae. The calybium (nut) resembles a pointed acorn; the cupule (casing) is hard like that of beechnuts and spiny like that of chestnuts. Three thickened ridges run the length of the calybium's shell.
Trees; branches and leaf blades glabrous. Young shoots reddish brown, slightly angulate. Petiole 1.5-2.5 cm; leaf blade oblong, ovate-elliptic, or obovate-elliptic, 7-15 cm, leathery, adaxially silver-gray with age, base rounded to broadly cuneate and usually inaequilateral, margin from middle to apex serrulate or rarely entire, apex acuminate, cuspidate, or shortly caudate; midvein slightly impressed from base to middle and slightly raised from middle to apex; secondary veins 10-15 on each side of midvein, prominent to very slender, evident. Rachis of inflorescences glabrous. Female inflorescence ca. 15 cm. Infructescences 8-15 cm. Cupule globose to subglobose, 1.2-1.5 cm in diam., completely or almost completely enclosing nut, irregularly valved, outside yellowish brown puberulent, wall to 1 mm thick; bracts scalelike, 3- or 4-angled, sometimes only base connate, in annular umbones. Nut 1(-3) per cupule, subglobose, 1-1.4 cm in diam., tomentulose, apex mucronulate; scar basal, 7-9 mm in diam. Fl. Apr-May, fr. Oct-Nov.
Broad-leaved evergreen forests; 200-1000 m. Anhui, Fujian, Guangxi, NE Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, E Sichuan, Zhejiang. The nuts are used for food.