Updated: Jun 22
Truth be known, I have not specified Koelreuteria paniculata in any of my designs, and I am not sure why. Perhaps one reason is that it rarely catches my eye; while the flowers of goldenrain trees are considered showy, I somehow missed their delicate displays in midsummer. That might simply be due to an overabundance of flashy crape myrtles dominating the summer urban landscape. Another reason could be that flowering and maturing seed pods (shown here) may occur at the same time, leaving this tree to appear a bit messy. Neither are really good reasons to miss an opportunity to use this hardy tree.
Recently, as part of my day job, the city arborist has been recommending them for some new developments to include as street trees, which helps to diversify the urban forest. Their mature size meets the perfect standard for street trees planted 35' on center across a project frontage, about 35' tall and slightly wider. Sunset notes their tolerances for urban conditions, such as "heat, drought, wind and air pollution" (p. 395), so K. paniculata is a win win for urban settings. For private gardens, the flowering and decorative value of the dried seedpods will provide added value should project owners desire their use over clean up when they eventually fall.
Curious note: The photo of the full tree in the slideshow below, by Jacinta Lluch Valero, is titled as "Jabonero de China" leading me to believe this might be a common name in Spain. Can anyone confirm this? The seedpods really do look like habaneros.
'Coral Sun': Nonflowering, so less clean up. New growth is tinted coral turning green as the foliage ages, then once again turning orange-red in autumn. The leaves appear to be more finely cut, lending to an attractive texture and seasonal color. Several sources observe that fall color is not reliable for the non-cultivar species, so it is unclear to me if this or other cultivars will display their color regardless of California's more mild climates (p. 394). If anyone out there has experience with 'Coral Sun', I would appreciate hearing from you.
'Fastigiata': Best for restricted spaces, such as between houses, reaching 25' but only 3' wide.
'Gocanzam' (Golden Candle™): Similarly fastigiate, reaching 35' tall by 4' wide.
'Rose Lantern': For floriculture and aesthetics, this might be the most desirable with pink tinted seedpods.
Coincidentally, Bay Area landscape architect, Jeff Wortham, provides this overview starting with a similar admission to mine of not utilizing this tree in designs.
Botanical Name: Koelreuteria paniculata
Koelreuteria: Honoree, botanist Joseph Gottlieb Kölreuter
Paniculata: Having flowers arranged in panicles
Common Name: Maidenhair tree
Family Name: Ginkgoaceae
Origin: Eastern Asia
Positioning: Lawn, urban spaces, background, cultivars for narrow spaces
Garden Themes: Children's, pollinator, drought
Uses: Shade, street tree, courtyard/patio, screen, floriculture
Type: Deciduous tree
Form: Round, open
Size: 35' tall by 40' wide
Outstanding Feature(s): Flower, fruit
Bark: Light green when young turning light gray and fissured with age
Type: Odd pinnately compound to bipinnately compound
Shape: Ovate leaflets
Margin: Crenate, serrate, or lobed
Color: Medium green, may or may not turn yellow in autumn. See cultivars for variation
Flower: Summer. Pyramidal panicles of star-shape small yellow flowers, showy
Fruit: Summer to winter. Papery 3-valved capsules have appearance of lanterns, green turning yellow then brown.
cultural requirements, tolerances & problems
Sunset Zones: A2; 2-24
USDA Zones: 5-9
Light: Full sun
WUCOLS SF Bay Area Hydro Zone: Moderate
Texture: Sand, loam, clay, well composted
Moisture Retention: Well-drained. Accepts periods of dryness
pH: Highly acidic to highly alkaline
Tolerances: Drought, heat, pollution, wind, shallow soils
Problems: Fruit drop may be messy and persistent; leaf clean up
Branch Strength: Medium
Insects: Borers, scale
Disease: Root rot, verticillium, leaf spot, canker
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
Extension Gardener. "Koelreuteria paniculata." North Carolina State University, Raleigh. Accessed on October 25, 2021, from https://plants.ces.ncsu.edu/plants/koelreuteria-paniculata/.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Plant Finder. "Koelreuteria paniculata." Missouri Botanical Garden, St. Louis. Accessed on October 25, 2021, from https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=a550.
SelecTree. UFEI. "Koelreuteria paniculata Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on October 25, 2021, from https://selectree.calpoly.edu/tree-detail/779.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on October 17, 2021.
Bark detail: "Koelreuteria paniculata, Sapindaceae, Goldenrain Tree, Pride of India, Varnish Tree, China Tree, bark; Stadtgarten Karlsruhe, Germany" by H. Zell is licensed under Creative CommonsAttribution-Share Alike 3.0 Unported.
Leaf detail: "Baden-Baden-Koelreuteria paniculata-50-Blasen-Esche-Blatt-2012-gje" by Gerd Eichmann is licensed under Creative CommonsAttribution-Share Alike 4.0 International.
Seed detail: "Koelreuteria paniculata (Golden Rain Tree, Panicled Goldenrain Tree)" by Plant Image Library is licensed under ShareAlike 2.0 Generic (CC BY-SA 2.0).