About Koelreuteria bipinnata Franch.
Koelreuteria bipinnata Franch. has alternate, bipinnately compound leaves. Leaflets are ovate with pinnate venation, are green in color, turn yellow in autumn, and grow 5–10 cm long. The species produces small yellow flowers that have a red tint at their base. Each flower has four petals, and flowers are borne on large branched panicles that measure 20–50 cm long. Flowers are showy, carry a pleasant fragrance, and are hermaphroditic, containing both male and female reproductive organs. Flowering occurs in July to August during summer; in more northerly locations such as central Europe, flowering takes place in September. The fruit is a three-lobed, inflated papery capsule 3–6 cm long with a faint reddish color, and is also showy. Each capsule holds several hard, nut-like pink seeds that are 5–10 mm in diameter. This tree has thin brown bark. Its branches initially grow upright, but bend downward somewhat as the tree matures. Branches may break due to poor collar formation, so pruning is required to develop a strong branching structure; pruning can also be done to form a single stem if desired, and to create clearance for pedestrians and vehicles when necessary. The tree is classified as weak-wooded. In landscapes where it grows well, Koelreuteria bipinnata is commonly used as a focal point. It is frequently planted as a street tree along highways, in parking lots, as a shade tree, and as a garden or specimen tree. The seeds are used to make beads for necklaces, and the flowers can be processed to produce a yellow dye.
