Poison-oak

Toxicodendron pubescens
Family: Anacardiaceae

Natural History
Poison-oak leaves showing the three leaflets with rounded lobes
Photo credit: SFRC, University of Florida

Poison-oak is a small, erect shrub that commonly grows up to 3 feet tall. It gets its common name from the compound leaves formed of three lobed leaflets that look like oak leaves. The plant is deciduous and the leaves turn red in the fall before they drop. Poison-oak spreads by sprouting from underground stems, called rhizomes, and by seeds. The sap in poison-oak contains a toxic substance, called urushiol, which can be harmful to susceptible people.

Poison-oak grows in dry ecosystems with sandy soils and poor nutrient availability such as sandhills, scrub, hardwoods, and other pinewood habitats. It is found from Florida, west to Texas, north to Kansas, and east to New Jersey; although it is most common along the coastal plain.

White-tailed deer and other small mammals browse on the leaves and its fruits. Many species of songbirds eat the fruits.

All parts of the poison-oak contain urushiol, an oleoresin and allergen, which causes inflammation, swelling, and itching in susceptible individuals. It can be picked up by touching any part of the plant. Historically, Native Americans used poison-oak sap to dye baskets. Today, poison-oak is sometimes used for arthritis pain.


 

Identifying Characteristics

Habitat: This shade-intolerant species grows well in dry habitats.
Size/Form: Shrub that reaches a maximum of 3' in height. This non-climbing plant has subterranean runners.  
Leaves: Leaves are alternate with multi-lobed leaflets (three leaflets per leaf). Although this plant is not related to the true oaks in the genus Quercus, the lobing on the leaflets makes the plant look oak-like. Leaflets are ovate to elliptic, growing up to 4" long, and up to 2 1/2" wide. Lobed or toothed margin. Leaves are a dull green and have hairs on both sides. Young twigs may be pubescent but older stems become glaborous. This plant contains toxic substances and skin contact with it can cause severe irritation to some people.
Fruit: Drupes are spherical, smooth or lightly pubescent, and up to 1/3" in diameter. Older drupes have shallow longitudinal grooves.

 

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