6. Koelreuteria Laxmann, Novi Comment. Acad. Sci. Imp. Petrop. 16: 562. 1772.
栾树属 luan shu shu
Trees or shrubs, deciduous, polygamo-monoecious or polygamo-dioecious. Leaves imparipinnate or bipinnate, estipulate; leaflets alternate or opposite, usually serrate or parted, rarely entire. Thyrses terminal, rarely axillary, large; branches many, spreading. Flowers zygomorphic. Sepals (4 or)5, valvate, outer 2 smaller. Petals 4 or sometimes 5, slightly unequal in length, adaxially with 2-lobed scales at base, clawed. Disk thick, apex often crenate. Stamens often 8, sometimes fewer, inserted on disk; filaments distinct, often villous. Ovary 3-loculed; ovules 2 per locule, on upper half of middle axis; style short or slightly longer; stigma 3-lobed or entire. Capsules swollen, ovoid, ellipsoid, or subglobose, trigonous, loculicidal into 3 schizocarps; carpels membranous, reticulate. Seeds 1 per locule, globose, arillodes absent; testa black, crustaceous; embryo revolute, radicles slightly longer. 2n = 22, 30, 32.
Three species: S China (including Taiwan), Japan, and perhaps Fiji; three species (two endemic) in China.