Rhus aromatica var. arenaria

Shrub highly variable, 0.6 - 2 m tall, spreading 1.8 - 3 m Leaves: alternate, stalked, with three leaflets (trifoliate). Leaves are aromatic when rubbed. Flowers: either male or female, borne on separate plants (dioecious), or with some bisexual flowers (polygamous), pale yellow, borne at ends of branches, with male flowers in 2.5 cm catkins and female flowers in short spike-like clusters. Flowers mature after the leaves expand. Male catkins persist through winter. Fruit: fleshy with a center stone (drupe), 4 - 5 mm long, bright red, densely hairy, sometimes persisting into winter but losing color. Twigs: highly branched, slender, hairy, aromatic when rubbed, with circular, raised leaf scars. Buds: yellow, tiny, hairy, surrounded by leaf scar. Leaflets: very short-stalked or stalkless, medium green, often glossy above, egg-shaped, coarsely toothed, with a lower surface that is hairy when young. The terminal leaflet is 1.5 - 4 cm long, fan-shaped to inversely egg-shaped with a blunt to rounded tip and a wedge-shaped base. Lateral leaflets about half the size of terminal leaflets. Fall color is orange to red to reddish purple.

Similar species: The similar Rhus aromatica var. aromatica has larger, elliptic to four-sided terminal leaflets (4 - 8 cm long) that taper to a short pointed tip and wedge-shaped base, lateral leafets with an outer margin that becomes rounded toward the base, and flowers that mature while or before leaves expand.

Flowering: late April to early June

Habitat and ecology: Rhus aromatica var. arenaria is characteristic of the Lake Michigan foredunes in Indiana. It also grows in sandy black oak savannas and low dune ridges near Lake Michigan.

Occurence in the Chicago region: native

Etymology: Rhus is the Greek name for a species of sumac. Aromatica means aromatic. Arenaria comes from the Latin word, arena, meaning sand.

Author: The Morton Arboretum

From Flora of Indiana (1940) by Charles C. Deam

This shrub was formerly frequent on the low dunes near Lake Michigan in Lake County but is infrequent in Porter County. The building of Gary, Indiana Harbor, and Whiting has covered most of its original habitat.

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Indiana Coefficient of Conservatism: C = 10

Wetland Indicator Status: UPL

Diagnostic Traits: compared to var. aromatica, var. arenaria produces flowers as the leaves expand; the terminal leaflets are smaller (1.5-3.5 cm), rounded at the apex and persistently velvety beneath.