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FOC | Family List | FOC Vol. 4 | Betulaceae

1. Corylus Linnaeus, Sp. Pl. 2: 998. 1753.

榛属 zhen shu

Shrubs or trees deciduous. Leaves alternate, petiolate, margin doubly serrate or lobulate. Male inflorescence pendulous, subsessile, cylindric, spicate-cymose, naked during winter, with numerous overlapping bracts; bracts each usually subtending 2 bracteoles and 1 male flower; stamens 2-8, inserted at middle part of bracts; anthers with 2 separate thecae, often pubescent at apex. Female inflorescence a compact cluster of several flowers; bracts campanulate or forming a tubular sheath, apex usually lobed; flowers paired, enclosed by a bract; calyx adnate to ovary, 4-8-lobed at apex; ovary with 1 or rarely 2 ovules in each cell; style 2-cleft to base. Fruit a subglobose or ovoid nut, enclosed or surrounded by enlarged bracts.

About 20 species: China, Japan, Korea, Mongolia, Russia; Europe, North America; seven species (four endemic) in China.

Corylus formosana Hayata (Gen. Ind. Pl. Form. 72. 1916) was described from Taiwan but no specimen is extant. It was treated as an uncertain species by J. C. Liao in Fl. Taiwan, ed. 2.


1 Bracts forming a tubular sheath, constricted above nut; nut enclosed by bracts.   (2)
+ Bracts together campanulate, not constricted above nut; nut surrounded by bracts.   (4)
       
2 (1) Shrubs; leaf margin lobed distally   7 Corylus mandshurica
+ Trees; leaf margin irregularly and doubly serrate.   (3)
       
3 (2) Bracts pubescent, with prominent ribs, divided into linear lobes, usually forked at apex   5 Corylus chinensis
+ Bracts tomentose, with faint ribs, divided into triangular-lanceolate lobes, usually not forked at apex   6 Corylus fargesii
       
4 (1) Lobes of bracts forming dense, branching spines   1 Corylus ferox
+ Lobes of bracts not forming spines.   (5)
       
5 (4) Bract limb deeply divided into linear, lobulate lobes, lobes often reflexed   2 Corylus wangii
+ Bract limb shallowly divided into ovate or ovate-lanceolate lobes, lobes not reflexed.   (6)
       
6 (5) Branchlets yellow tomentose; petiole 0.7-2.2 cm, yellow tomentose; leaves suborbicular to broadly ovate or obovate, abaxially tomentose, margin irregularly and doubly serrate; bracts ca. as long as or shorter than fruit   3 Corylus yunnanensis
+ Branchlets sparsely villous; petiole 1-3 cm, loosely villous or glabrescent; leaves ovate, oblong, or elliptic, pilose along veins abaxially, margin lobulate or incised distally; bracts longer than fruit   4 Corylus heterophylla

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