Trees. Branches tuberculate, lenticels orbicular to elliptic. Leaves spreading, bipinnate, axes and adaxial surface of petiole often with one line appressed pubescent; leaflets 9–17, alternate, rarely opposite; petiolules short or leaflets subsessile; blades obliquely ovate, papery or subleathery, abaxially densely pubescent, adaxially glabrous or hairs on midvein, base broadly cuneate or rounded, slightly oblique, margin incurved serrate or sometimes entire. Thyrses spreading, large, hairy. Calyx 5-lobed to middle; sepals broadly triangular or elliptic, hispidulous and fimbriate glandular, margin erose. Petals 4. Stamens 8, filaments spreading white villous; anthers short and sparsely hairy. Ovary trigonous-ellipsoid, pilose. Capsules pale purplish red, brown when mature, ellipsoid or subglobose, 3-ridged, apex obtuse or rounded, mucronate; carpels ellipsoid to subcordiform, abaxially reticulate veined, adaxially shiny. Seeds subglobose.
3. Koelreuteria elegans (=Koelreuteria henryi)
Trees. Branches ridged, pubescent. Leaves bipinnate, with long petiole; leaflets 5–13; blades oblong-ovate, varied in shape and size, subleathery, abaxially glabrous or only barbate at vein axils, base extremely oblique, margin slightly incurved serrate or nearly entire below middle, apex long acuminate to caudate. Thyrses terminal, large, branches and pedicels pubescent. Flowers yellow, Sepals 5, oval or ovate-triangular, ciliate. Petals 5, lanceolate or oblong, with 2-lobed, tuberculate toothed scale, claw hairy. Stamens 7 or 8; filaments hairy. Capsules inflated, ellipsoid, 3-ridged. Seeds black and globose.
endemic species in Taiwan