Koelreuteria spp.
golden rain tree
Overview
Koelreuteria spp. is a small genus of three or four species of deciduous trees in the soapberry family (Sapindaceae), native to eastern Asia. Trees reach 20-40 ft (6-12 m) tall with a rounded, spreading crown of similar width. The leaves are alternate and pinnately or bipinnately compound, 6-18 in (15-45 cm) long, with coarsely toothed or lobed leaflets that open pinkish, mature mid-green, and turn yellow before autumn leaf fall. In summer the branch tips carry large, open panicles of small yellow flowers 8-18 in (20-45 cm) long, each bloom about 0.4 in (1 cm) across with a red basal spot. Flowering is followed by inflated, papery, three-sided seed capsules resembling small lanterns, 1-2 in (2.5-5 cm) long, that ripen from green through pink to tan and hold black round seeds. The genus is native to China and Korea, and K. paniculata extends to Japan. K. paniculata self-seeds freely and has naturalised as a weedy tree in parts of North America and Australia. The wood is brittle and prone to limb breakage in storms.
Native Range
The genus is native to eastern Asia, in China and Korea, with K. paniculata also reaching Japan. Species grow in mixed woodland, on slopes, and along valley margins.Suggested Uses
Grown as a street and shade tree for small to medium spaces, planted for late-summer flowering and tolerance of difficult urban soils. K. paniculata is used where a compact, drought-tolerant flowering tree is wanted, away from areas where its self-seeding is unwelcome.How to Identify
Appearance
Size & Dimensions
Height20' - 40'
Width/Spread20' - 40'
Reaches mature size in approximately 20 years
Bloom Information
Flowering comes in mid- to late summer, later than most flowering trees, when broad panicles of yellow blooms open at the branch tips over two to three weeks. Fallen flowers leave a yellow carpet beneath the canopy. The papery capsules that follow hold visual interest into autumn as they shift from pink to tan.
Detailed Descriptions
Flower Description
yellow with red baseFoliage Description
green, pink when young, yellow in autumnGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Trees grow in full sun and tolerate a wide range of soils, including poor, dry, alkaline, and compacted ground. Established plants are drought-tolerant and withstand urban heat, pollution, and wind. Wet, poorly drained soils are the main limit on growth. Young trees gain from formative pruning to build a strong branch structure, since the wood is brittle. Watering is needed mainly during establishment and in extended drought. Self-sown seedlings appear readily around mature trees and may need removal.Pruning
Formative pruning in the first years, done in late winter, builds a sound framework and reduces later limb failure in the brittle wood. Crossing and weak branches are removed while small, as large cuts on this genus close slowly.Pruning Schedule
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winter