ORIGIN: North America

PATHWAYS: horticulture

POSSIBLE TO DETECT: year-round

FLOWERING SEASON: June – July

DESCRIPTION: Small tree or shrub with a wide, spreading, open crown. Leaves large, pinnately compound with  13–27 lanceolate leaflets which have serrate margins (in a cultivated form deeply divided). Rachis of leaflets, twigs and young branches are covered with fine hairs. Flowers small, greenish-yellow, borne in upright clusters. Fruits are fuzzy, red, borne in upright, conical, dense clusters which remain on plants until next spring.

HABITAT: Ruderal sites, forest margins and clearings, mostly on dry soil. It is mainly spreading vegetatively with transported soil and because of this it is often found at roadsides.

STATUS: Recorded locally throughout Europe.

SIMILAR SPECIES: Tree-of-Heaven (Ailanthus altissima) has similar large, pinnately compound leaves, which have large, glandular teeth near the base but the leaf margin is not serrated. Twigs and branches are not covered with hairs. Fruits are single samaras. Shining sumac (Rhus copallinum) has prominent wings on rachis between the leaflets, fruit clusters are loose and hanging. Smooth sumac (Rhus glabra) does not have hairs on leaflets and young branches.

SOURCE: Field Guide to Invasive Alien Species in European Forests