Dropping golden yellow flowers in mid-summer and conspicuous yellow leaves in autumn, the Golden Rain Tree is a small, irregularly shaped tree from China, Japan, and
the Koreas. They produce distinct three-lobed seed pods vaguely resembling Chinese lanterns which persist well into autumn.
Koelreuteria paniculata (Golden Rain Tree, Varnish-Tree)
Family: Sapindaceae (Soapberry family)
Subspecies: ‘Fastigiata’ (erect growth habit)
Native: China, Japan, Korea
Hardiness Zones: 5b-9b
Height: to 12m
Diameter: to 12m
Root System: coarse, few large roots, woody
Growth Rate: moderate (32-60cm annually)
Age: typically to 50 years
Monoecious/dioecious: monoecious (almost always)
Tolerates: drought (moderate), flooding, heavy soils, alkaline soils, salt spray (moderate), air pollutants, rarely attacked by pests
Problems (major): verticillium wilt (begins on single branches, may be fatal)
Problems (minor): root rot, leaf spot, canker (produces sunken dead patches on bark), weak/brittle wood, invasive mostly in warm climates (ex. Florida)
Poisonous: foliage toxic to livestock (horses, cattle, etc.)
Soil requirements: tolerant of light sand, heavy clay, and alkaline soils, prefers slightly dry, well-drained soils
Air requirements: tolerates air pollutants
Watering requirement: dry to moderate
Sun requirement: full sun
Leaves: initially pink/brown/purple turning medium green becoming shades of yellow in autumn, pinnate/partially bipinnate, oblong/ovate, serrated with coarse teeth, compound, 7-17 irregularly lobed leaflets (sometimes with small secondary leaflets narrower but similar in shape) under 10cm, leaflets with short petioles or sessile, rachis light green or red and smooth (glabrous) or somewhat pubescent, to 45cm
Flowers: blooming May-July (earlier in warmer zones) on terminal panicles, 4 green sepals, 4 golden yellow petals wide but lanceolate, 8 yellow stamens, usually perfect/hermaphroditic, lasting 2-4 weeks, individual flowers to 1cm, to 38cm
Fruits: thin/paper-like, vaguely lantern-shaped or pyramidal (3-lobed), dry, dehiscent, 1 seed per lobe, individual seeds globe-shaped to 8mm
Seeds require stratification: no
Seed dispersal: likely wind
Form: irregular, vaguely globe-shaped
Trunk: short, to 38cm wide, flat gray ridges with red-brown fisures, lenticels scattered amongst trunk
K. bipinnnata may be more showy, but K. paniculata is much more cold tolerant.
This tree is useful as a moderately fast growing shade tree with showy flowers and falling foliage, explaining the name ‘Golden Rain Tree’ in midsummer once the flowers fall and in autumn again when the leaves drop.
All of the images provided were taken by me. They may be used for educational/informational purposes only, provided that this article/online journal is appropriately cited first.