Side by side
Ash or tree of heaven? How to tell them apart
Fraxinus excelsior · Ailanthus altissima
How to tell them apart – ash: opposite leaves with toothed leaflets; tree of heaven: very large pinnate leaf with 13–41 leaflets, each with 1–3 coarse teeth at the base, stinks when crushed.
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How do you recognise them?
- Ash
- Opposite pinnate leaves with 9–13 leaflets and thick, matt black buds.
- Compared with tree of heaven: opposite leaves with toothed leaflets.
- Tree of heaven
- Very large pinnate leaf with 13–41 leaflets, each with 1–3 coarse teeth at the base; stinks when crushed.
| Ash | Tree of heaven | |
|---|---|---|
| Leaves | Opposite, pinnate with 9–13 oblong, toothed leaflets. The leaves often fall while still green in autumn. | Alternate, pinnate, 40–90 cm long with 13–41 leaflets. These are untoothed apart from 1–3 coarse teeth near the base, with a small gland beneath. |
| Flowering | April | June–July |
| Fruit | Clusters of winged fruits (‘keys’) that hang on well into winter. | Clusters of twisted winged fruits that turn red to brown. |
| Bark | Smooth and greenish-grey when young, later pale grey with a fine network of ridges. Buds velvety black. | Smooth, grey with pale vertical stripes. |
| Shape and height | Broadleaf tree, 20–35 m | Broadleaf tree, 15–25 m |
| Site | Sun or partial shade, any garden soil, moist to wet | Full sun, any garden soil, dry |
| Native to Belgium | Yes | No, an invasive alien species |
| Good for bees, butterflies and birds | Yes, for butterflies and birds | Little |
| Poisonous to people and pets | Not known to be poisonous | Not known to be poisonous |
| Pruning months | November–March | Better removed than pruned |
What does it mean for your garden?
- Tree of heaven is an invasive non-native species: do not plant it. Pull up seedlings and choose a native species instead.
- Ash is native: it feeds more insects and birds than a non-native species. If in doubt, choose this one.
- Ash (20–35 m) and tree of heaven (15–25 m) both grow into large trees: too big for an ordinary garden, but fine in a large garden, a park or a meadow.
Read on
- Plant profile: Ash
- Plant profile: Tree of heaven
- Ash: when and how to prune
- Identification key: the question that separates them
Also looks like
- Ash or rowan
- Walnut or tree of heaven
- Ash or elder
- Ash or Japanese pagoda tree
- Ash or manna ash
- Ash or box elder
- Golden rain tree or tree of heaven
Identify by feature
This comparison is compiled from the Bladwijzer species pages.