Koelreuteria elegans subsp. formosana

Golden Rain Tree originates from eastern Asia – Japan, China and Korea – and has been widely planted in eastern Australia, including at Crystal Waters. It is not yet listed as a priority weed for the Sunshine Coast region, although it is an “Alert” species for the Brisbane region. It is concerning at Crystal Waters because seedlings seem to be appearing in abundance in certain areas, for example near the cemetery. It is a known environmental weed in a number of areas around the world, invading bushland and outcompeting native species. It is particularly challenging here, because it is quite similar to white cedar, which is a native pioneer species which we want to see in restoration areas. Below I will explain how to distinguish them. It doesn’t appear in the Sunshine Coast Council’s Biosecurity Plan 2024 (which you can find here), but I treat it as a “locally significant species”, with the aim of controlling and preventing its’ spread when it is impacting or threatening high value natural areas. More information on it can be found here.

Information and Identification

Golden Rain Tree is spectacular when it is flowering and fruiting – unfortunately, as it fruits so prolifically, the seeds get spread around and come up everywhere. As the seeds have a papery shell, they can be dispersed by wind as well as water.

Identification:

Medium tree approximately 5-12m tall.
Twice-compound leaves with numerous leaflets: each “leaf” is very large, with stems then sub-stems ending in leaflets. The stems of these leaves are often reddish when they’re newly leafed out (see below). It’s the arrangement of these leaflets which distinguish between golden rain tree and white cedar. White cedar has the leaflets arranged in pairs (“opposite”) along the stems, while in golden raintree the leaflets alternate along the stems (mostly!). See the pictures below.
The flowers are bright yellow, with a reddish papery shell forming around the developing seeds.