Rhus glabra L.

Smooth Sumac


CC = 1
CW = 5
MOC = 72

© DETenaglia

Family - Anacardiaceae

Habit - Large shrub or rarely small tree, usually dioecious.

Stems - Ascending, to 5 m, branched. Young branches glabrous, glaucous (but note that inflorescence branches usually are sparsely hairy), the older branches usually with prominent lenticels.

Rhus_glabra_stem.jpg Stem and nodes.

© DETenaglia

Leaves - Alternate, pinnately compound with 11-21 leaflets, the petiole 6-11 mm long, glabrous, reddish purple, the rachis not winged. Leaflets 5-13 cm long, 1.5-3.0 cm wide, lanceolate to elliptic-lanceolate, sessile or very short-stalked, the margins toothed, the upper surface dark green, glabrous, shiny, the undersurface light green, glabrous, glaucous.

Rhus_glabra_leaflets.jpg Notice the serrate leaflets.

© DETenaglia

Inflorescence - Terminal, dense, ovoid panicles, 10-25 cm long, 5-10 cm wide.

Rhus_glabra_inflorescence.jpg Inflorescence.

© SRTurner

Rhus_glabra_inflorescence2.jpg Inflorescence branch.

© SRTurner

Flowers - Sepals 5, 1.6-2.0 mm long, narrowly ovate, sharply pointed at the tip, fused at the base. Petals 5, 2.0-2.5 mm long, oblanceolate, rounded at the tip, greenish yellow, sparsely hairy on the inner surface. Staminate flowers with the stamens 5, the anthers ovoid, usually shorter than the filaments. Pistillate flowers with the styles 3, appearing terminal, equal in length or nearly so, short, sometimes fused toward the base. Ovary with 1 locule.

Rhus_glabra_flowers.jpg Flowers.

© SRTurner

Rhus_glabra_flower.jpg Flowers.

© DETenaglia

Fruits - Fruits 4-6 mm long, 4-5 mm wide, somewhat flattened, red, with dense, minute, stout, red glandular hairs.

Rhus_glabra_infructescence.jpg Infructescence.

© SRTurner

Flowering - May - July.

Habitat - Forest openings, open woods, prairies, fencerows, roadsides, railroads.

Origin - Native to U.S.

Lookalikes - R. copallinum, R. typhina.

Other info. - This shrub is common throughout Missouri and the eastern half of the continental U.S. and some regions farther west. It is present to some extent in every state in the contiguous 48 and also ranges into Canada and Mexico. It is an easily recognized species by virtue of its compound leaves with toothed leaflets. Unlike R. copallinum, the leaf rachis is not winged, and unlike R. typhina (which is rare in Missouri), the branches are glabrous.

The plant is very common in many of the habitats mentioned above, and threatens some prairies with an overabundance of woody growth. If left unchecked this can eventually destroy the prairie. The photo below shows a section of prairie which has been largely subsumed by R. glabra.

Rhus_glabra_invasion.jpg Section of prairie near Illiniwek Village, MO, which has been overrun by Rhus glabra.

© SRTurner

Traditionally this species was used heavily by natives to treat numerous ailments. The leaves were once boiled and made into a tea to help remedy asthma, diarrhea, and dysentery. A root tea was used as a diuretic. The berries of this plant can be steeped in water to prepare a pleasantly tart beverage not unlike lemonade. The tea is caffeine-free but rich in Vitamin C. It is best to use cold water to brew this "sumac-ade," as hot water releases bitter tannins. Provided that ripe, deep red berries are used, there is no danger of confusing these plants with poison sumac, which has whitish berries. The dried fruits of some sumac species are ground and used as a sour seasoning in Middle Eastern cuisines.

Photographs taken at Dave Rock Conservation Area, St. Clair County, MO., 6-7-03 (DETenaglia); also at Busch Wildlife Area, St. Charles County, MO, 8-10-2007 and 6-12-2009, Klondike County Park, St. Charles County, MO, 5-29-2017, and Illiniwek Village SHS, Clark County, MO, 7-8-2017 (SRTurner).