Description from Flora of China
Koelreuteria bipinnata var. puberula Chun; K. bipinnata var. integrifoliola (Merrill) T. C. Chen; K. integrifoliola Merrill.
Trees, to 20 m tall. Branches tuberculate, lenticels orbicular to elliptic. Leaves spreading, bipinnate, 45-70 cm; axis and adaxial surface of petiole often with one line appressed pu-bescent; leaflets 9-17, alternate, rarely opposite; petiolules ca. 3 mm or leaflets subsessile; blades obliquely ovate, 3.5-7 × 2-3.5 cm, papery or subleathery, abaxially densely pubescent or sometimes mixed with appressed hairs, adaxially glabrous or pilosulose on midvein, base broadly cuneate or rounded, slightly oblique, margin incurved serrate or sometimes entire. Thyrses spreading, large, 35-70 cm, pubescent with pedicels. Calyx 5-lobed to middle; sepals broadly triangular or elliptic, hispidulous and fimbriate glandular, margin erose. Petals 4, oblong-lanceolate, 6-9 × 1.5-3 mm, apex obtuse or acute, claw 1.5-3 mm, villous; scales deeply 2-lobed. Stamens 8, 4-7 mm; 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, 4-7 × 3.5-5 cm, apex obtuse or rounded, mucronate; carpels ellipsoid to subcordiform, abaxially reticulate veined, adaxially shiny. Seeds subglobose, 5-6 mm in diam. Fl. Jun-Sep, fr. Aug-Oct.
● Sparse forests, slopes; 400-2500 m. Guangdong, Guangxi, Guizhou, Hubei, Hunan, Sichuan, Yunnan.