Rhus glabra aka Smooth Sumac

Rhus glabra, or smooth sumac, belongs to the cashew family. Its native range runs from Canada to northern Mexico. This deciduous shrub also grows as a small tree. It lives in prairies, open woods, and disturbed ground. It also grows on dry, rocky slopes and in canyons. Garden plants often reach 8–15 feet [2.4–4.6 metres] tall and wide. RHS gives a smaller range of 5–8 feet [1.5–2.5 metres]. Its loose, uneven shape spreads through root suckers. These shoots can build dense colonies beyond the original plant.

The stout stems lack hairs and carry a pale waxy coat. Older bark turns brown-gray, with shallow cracks and small bumps. The leaves grow in an alternate pattern along the stems. Each pinnate leaf has many narrow leaflets with toothed edges. Their upper sides shine dark green; the undersides look pale. The long leaves give the shrub a fern-like look. Fall brings yellow, orange, or red shades before leaves drop.

Small yellow-green flowers form upright panicles from May to July. Male and female flowers grow on separate plants. Both sexes must grow nearby for females to bear fruit. Red drupes form on female plants from August to October. Sticky red hairs cover these small fruits. Their dense clusters stay on bare branches through winter. Birds and small mammals eat them during the cold months. Butterflies visit the flowers for nectar. The plant also hosts larvae of the red-banded hairstreak.

Grow smooth sumac in sun or part shade. Full sun helps bring out strong fall color. It accepts sand, loam, clay, and poor rocky ground. Soil must drain well; wet ground does not suit it. It tolerates drought and dry soil once growing well. Sources place it in USDA zones 3–9 and UK class H6. Plant groups can hold soil on banks and cover rough ground. Its spread suits wild gardens better than small shrub borders. Leaves yield black ink, while the wood supplies pigments.

Few pests or diseases cause major trouble. Aphids, scale, mites, leaf spot, and rust may occur. Honey fungus, coral spot, and Verticillium wilt are also possible. Root suckers can make the plant hard to contain. The sour fruit can flavor a drink after soaking. Boiling can draw out tannins and make it harsh. Reports of edible roots come with warnings about possible toxicity. Reports of sap causing skin rash remain unconfirmed. Traditional medicinal use does not establish that all parts are safe.