Pronounciation: Cole-reu-TEAR-ee-a pan-ic-u-LA-ta

Hardiness zones:
Sunset All
USDA 5-11

Landscape Use: Deciduous shade tree for oasis and mesic landscape design themes, floral and fruiting accent, fall color.

Form & Character: Graceful, upright and rounded, tough and rugged, yet refined due to foliar texture, seasonally colorful.

Growth Habit: Deciduous, woody perennial tree, deterministic, moderate growth rate to 30-feet tall with equal of greater spread, polygamo-monoecious or polygamo-dioecious, stems prominently lenticellate, trunk phellum gray brown, rough and somewhat fissured.

Foliage/Texture: Glabrous leaves pinnately compound, 6- to 12-inches long, 5 to 17 leaflets with blunt serrate margins, medium green, distinct pinnate veination, rachis canaliculate to flattened adaxially, emergent leaves in early spring are pinkish bronze to purplish in color; medium texture.

Flowers & Fruits: Zygomorphic ("yoke shaped") yellow flowers with 4 to 5 petals present in large terminal panicles to 16-inches long, strongly attracts bees; papery thin fruits are 3 to 4 part inflated bladderlike pods, like little Chinese lanterns, greenish yellow when immature ripening to pinkish or brown, seeds brown to mostly black, reported to be edible when roasted.

Seasonal Color: Floral accent (late spring to early summer), fruit accent (late summer into autumn), deciduous foliar color (late fall and early winter).

Temperature: Cold hardy, heat stress injury above 115^oF.

Light: Full sun

Soil: Tolerant

Watering: Bi-weekly supplemental deep irrigations are a baseline requirement during the Phoenix summer for survival. Supplemental water generally not needed during the winter months.

Pruning: Crown raise slowly and purposefully (not aggressively) as the tree matures. Prune during winter. Excessive crown raising can predispose golden rain tree's trunk to sunscald injury from afternoon western summer desert sun.

Propagation: Primarily seed (cold stratify at 40^oF for 2 to 3 months before sowing), but can be propagated asexually by semi-softwood or hardwood stem cuttings, layering or root cuttings.

Disease and Pests: Canker and leaf spot diseases are possible, but are not common in Phoenix.

Additional comments: In Phoenix, golden rain tree is a rather "old fashioned" landscape tree similar to Melia azedarach (Texas umbrella tree) and is mostly seen in 'older more vegetated parts of town' (think Arcadia). It too is highly tolerant of urban conditions. It has many seasonal accents that are counterbalanced by its propensity to be quite messy, a real "Debbie downer" for all the landscape neat freaks. However, the 'Horticultural clods of Phoenix' (aka 'Hort clods') enjoy working around this tree as it gives them yet another reason to fire up their Echo leaf blowers at full throttle at 6 o'clock in the morning. Although golden rain tree can grow well in older more vegetated parts of Phoenix, it is better suited for landscape use in Arizona towns and cities above 2,500 feet in elevation.

Taxonomic tidbits: The genus name Koelreuteria honors Joseph Gottlieb Koelreuter (1733-1806), professor of natural history at Karlsruhe and a pioneer experimental investigator of plant hybridization. The specific epithet paniculata means 'in a panicle' in reference to the floral structure.

Ethnobotanical uses: Golden rain tree has a wide range of economic uses and has been utilized for high quality timber, making dyes, extraction of oil from the seeds as a lubricant, for soap and has a range of medicinal uses. In China, it has religious significance (Meyer, 1976) and has been cultivated around temples, palaces and gardens as a memorial tree which since the Chou Dynasty (1122–240 BC).

Literature citation: Meyer, F.G. (1976) A revision of the genus Koelreuteria (Sapindaceae), Journal of the Arnold Arboretum 57:129–166.