Koelreuteria elegans

Golden rain tree

Introduction

Taiwan native, Koelreuteria elegans,is a very popular landscape tree because of its colorful petals and rose colored fruit capsules. Even though this tree is loved and valued by many, we cannot ignore the invasive characteristics that initiated its appointment as a Category II exotic invasive. Koelreuteria is a fast growing plant that is able to grow in an array of environmental conditions.

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Description

Koelreuteria elegans is a deciduous tree that grows 25 to 50 feet in height, with a 35 to 50 foot diameter spread. The bark is furrowed lengthwise and corky. Leaves are bipinnately compound, ovate to oblong in shape, and arranged alternately on the stem. Flowers are yellow, 12 to 20 inches long, 8 to 10 inches wide, and densely pubescent. Fruit is oval but elongate in shape, varies in length from 1 to 3 inches, and is pink in color. The fruit can also be described as being an inflated papery capsule. Seeds are small and black.
Reproduction occurs via seed that is able to germinate fairly quickly, within a period of 6 to 8 days. Water may contribute to the spread of the seeds, although this has not yet been proven. Birds may also play a factor in the dispersal of the seed.

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Impacts

Introductions of Koelreuteria as an ornamental tree have made it possible for this tree to escape from cultivation and naturalize in Texas, Louisiana, Alabama, and Florida. Because it is a fast grower and has greater seed viability in warmer climates, Koelreuteria has the ability to crowd out desired native species.

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Management

Preventative:

The first step in preventative control of Koelreuteria is to limit planting and removal of existing plants within the landscape. If possible, removal should occur before seeds are produced.

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Cultural:

Inform the public to refrain from purchasing, propagating, or planting Koelreuteria due to its ability to escape into natural areas.

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Mechanical:

Larger trees may be cut, should be coupled with chemical treatment to avoid resprouting.  Small seedlings may be mowed or pulled by hand. 

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Biological:

There are no known biological control programs for Koelreuteria elegans.

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Chemical:  

There are no known chemical control programs for Koelreuteria elegans.  Cut stump treatments with 100% triclopyr are effective but should be applied to the outer lay of bark within 1 minute of cutting.  Foliar applications have not been tested for control of this species.

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Helpful Notes:

Surfactant – 0.25% is the standard rate for all foliar herbicide applications, 2 teaspoons per gallon.

Dry time – generally 4-6 hours is adequate, but the longer the better for glyphosate

Pay particular attention to herbicide labels near wetlands or bodies of water.

The use of trade names in these publications is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label.

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References and Useful Links:

Floridata Homepage

University of Florida Center for Aquatic and Invasive Plants

University of Florida’s Cooperative Extension Electronic Data Information Source

Langeland, K.A. and K. Craddock Burks. 1998. Identification and Biology of Non-Native Plants in Florida's Natural Areas. IFAS Publication SP 257. University of Florida, Gainesville. 165 pp.

The Plant Conservation Alliance's Alien Plant Working Group. Weeds Gone Wild: Alien Plant Invaders of Natural Areas

Pacific Island Ecosystems at Risk (PIER). Plant Threats to Pacific Ecosystems

Gilman, E.F. and D.G. Watson. 1993. Koelreuteria elegans: Flamegold. Fact Sheet ENH-496, a series of the Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida.

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