Smooth sumac is a thicket-forming shrub or small tree with a spreading crown.
Leaves are alternate, feather-compound, 12–16 inches long, with 15–23 leaflets; central leaf-stem smooth, lacking wings; leaflets with tip pointed, base rounded, margins coarsely toothed; upper surface dark green, shiny; lower surface lighter to conspicuously white, smooth; broken leaves exude a white sticky sap. Leaves turn red in fall.
Bark is grayish-brown, roughened with raised pores; smooth on young plants; older trunks with shallow grooves.
Twigs are stout, angular, smooth, with a whitish coating that can be wiped off.
Flowers late May–July, both male and female flowers in dense, much-branched clusters at the end of new growth, on separate plants; clusters 5–9 inches long; flowers numerous, petals 5, white.
Fruits August–September, compact clusters, erect, persistent; fruit round, about 1/8 in diameter, dark red with red velvety hairs, fleshy, 1-seeded; stone smooth, oval.
Similar species: There are four species of sumacs in Missouri.