tree of heaven Identification (Ailanthus altissima)

Check the overall leaf structure, bark, and seed clusters first.

• Leaves are alternate, once-pinnate, often 1 to 3 feet (30 to 90 cm) long.
• Each leaf usually has 10 to 41 leaflets arranged mostly opposite along the central stalk.
• Leaflets are mostly smooth-edged, with one or two coarse lobes near the base.
• Twigs are stout and smooth, with large leaf scars after leaves drop.
• Gray bark is fairly smooth on younger trunks, becoming shallowly ridged with age.
• Seeds hang in dense clusters; each seed sits inside a single twisted wing.

Dense hanging seed clusters can confirm the ID when present.

Ailanthus altissima shows clear visual shifts from seedling to fruiting adult, aiding identification.

• Seedling: Seedlings start with simple leaves, then quickly produce alternate compound leaves on stout green shoots, giving a sparse, upright look unlike older branched plants.
• Young plant: Young plants often form fast, vertical sprouts with very large compound leaves, sometimes 1-3 feet (30-90 cm) long, and few side branches.
• Mature plant: Mature trees develop a single trunk or several upright stems, a broad open crown, thicker gray bark, and more regular branching than younger shoots.
• Fruiting stage: Fruiting branches carry dense hanging clusters of flat twisted samaras, the papery winged fruits, which add a conspicuous layered texture absent before seed set.

In late spring to early summer, Ailanthus altissima shows very large compound leaves and loose clusters of small yellow-green flowers at branch tips. By late summer into fall, hanging winged seeds become prominent and often persist after leaf drop. In winter, the stout twigs, big leaf scars, and coarse open branching are easier to see.

Several pinnate-leaved trees are often mistaken for tree of heaven.

Ailanthus altissima is native to China and Taiwan. In its native range it occurs in lowland to lower montane areas, often along forest edges, open slopes, disturbed ground, roadsides, streambanks, and around settlements. Habitat is useful for identification because this species commonly appears in sunny, human-disturbed places rather than deep woodland. Finding a fast-colonizing tree on vacant lots, rail corridors, walls, or urban edges can help narrow an ID toward Ailanthus altissima, especially outside managed plantings.

• Skin contact: Sap and plant juices can irritate the skin in some people. The risk relates to contact with leaves, twigs, and cut stems, not just ingestion.
• Handling concern: Flowers, leaves, and other parts have a strong odor, and handling or cutting the tree can expose people to irritating plant material. This is mainly a human skin-contact concern.