Tree of heaven
Ailanthus altissima
Family · Simaroubaceae · Irritating
The tree that grows in any concrete crack, railway line or abandoned lot, at a rate no native can match. It came from China and is today one of the costliest invaders to fight in Europe.
Town and roadside · Roadsides and waste ground · Streams and ditches · Fields and pasture
Also known asstinking sumac, varnish tree
How to tell it
A huge compound leaf with fifteen to thirty leaflets, and the decisive sign is at each leaflet's base: one or two coarse teeth with a gland at the tip, which no other native tree has. Crushed, the leaf smells bad, like rancid butter. Winged fruits in reddish clusters.
What it is confused with
Narrow-leaved ash
Fraxinus angustifolia
Both have compound leaves and winged fruit. Ash has leaflets toothed along the whole margin and black buds in winter; tree of heaven has smooth-edged leaflets with two glandular teeth at the base, and smells bad.
What it is for
None to encourage
It suckers from roots tens of metres from the trunk and releases compounds that stop other plants growing, so cutting without treating the stump multiplies it. The sap causes dermatitis in sensitive people, and there are cases of myocarditis in those handling it unprotected.
The law says
An invasive alien species in Portugal and on the European Union list of species of concern. Do not plant or propagate it; control has its own methods.
Where it occurs
Each square is an area with recorded observations of this plant. The lighter background is the set of areas where any of the entries has been observed, and serves as a reference. Note what this is not: it is not where the plant lives, it is where people record it, so trails and towns always look fuller than the mountains. Data from GBIF.
Sources
Community
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