Last Updated on

Eastern poison oak:
Also known as Atlantic poison oak;
Toxicodendron pubescens

This variety of sumac, which causes dermatitis the same way as poison ivy is present in the southeast quarter of the United States. Its leaf is reminiscent of white oak. However, unlike Western poison oak, Eastern poison oak is not a creeper. It forms a shrub that can reach three feet (one meter) in height. Its leaves, which come in groups of three (again) are covered with small velvet bristles. Some botanists consider that small shrub as a subspecies to Western poison oak, but it is a separate species.

Eastern poison oak. Copyright Tim Vasquez (Wikipedia English).
Eastern poison oak. Copyright Tim Vasquez (Wikipedia English).

Leaf

Like Western poison oak, its leaf is reminiscent of white oak and it is easy to confuse. Its alternate leaves, in groups of three leaflets, are covered with small velvet bristles, which give it its latin term pubescens. Each leaflet can measure up to 6 in (15 cm) long. The appearance of the leaves can vary greatly from one plant to another. In the fall, the leaves turn to orange, like other toxicodendrons.

 Eastern poison oak (Toxicodendron pubescens)
 Eastern poison oak (Toxicodendron pubescens)
Eastern poison oak (Toxicodendron pubescens) hairy leaves.
Eastern poison oak (Toxicodendron pubescens) hairy leaves.

Trunk and stems

The color of the stems and trunk is a grayish brown. The stems are also covered with small velvet hairs which give them a fuzzy texture. The total height of the Eastern poison oak can reach 3 feet (1 meter) but usually grows to about 2 feet (60 cm) tall.

Eastern poison oak (Toxicodendron pubescens) whole shrub. Copyright alabamaplants.com
Eastern poison oak (Toxicodendron pubescens) whole shrub. Copyright alabamaplants.com

Flowers and fruits

The flowers in clusters, at the base of the stems, are pale, yellow green. These flowers are very small, often only half an inch (1 cm) in diameter and appear all throughout spring (April – May). The fruit is small, round, striped (like a pumpkin), and yellowish or greenish. It has small velvet hairs as the leaves. The fruits come in drupes near the flowers, at the base of the stems, and appear in late spring.

Eastern poison oak (T. pubescens) fruits. Source USDA
Eastern poison oak (T. pubescens) fruits. Source USDA

Propagation

This vigorous plant is propagated by its seeds, located within fruit. Its fruit can drop near the plant or birds can eat the fruit and expel the seeds later in their droppings. Another plant can then grow in this place, if the germination is done correctly. Eastern poison oak can also spread by rhizomes.

Habitat and distribution

Eastern poison oak is present in the southeast quarter of the United States, from Texas to New Jersey including Florida. This plant prefers poor and sandy soils (sandhills, dry hammocks, thickets, old fields) and is found in oak and pine forests. In the Eastern poison oak settlement area, you can also meet eastern poison ivy.

Eastern poison oak habitat area (Toxicodendron pubescens).
Eastern poison oak habitat area (Toxicodendron pubescens).

Videos about Eastern Poison Oak

Poison Oak – A Survival Guide

Resources about Eastern Poison Oak

Western poison oak:
Also known as Pacific poison oak;
Toxicodendron diversilobum

This toxicodendron is located along the Pacific coast. It comes in the form of a climbing vine or shrub. It is named “oak” because its leaf is reminiscent of white oaks, with some curves on the edge of the leaf. The western poison oak dermatitis looks much like poison ivy. The first European to discover western poison oak was David Douglas between 1825 and 1830 in the Columbia River valley (poor guy!).

Western poison oak growing as a climbing vine.
Western poison oak growing as a climbing vine.
Western poison oak growing as a brush.
Western poison oak growing as a brush.

Leaf

As Eastern poison oak, its leaf is reminiscent of white oak and it is easy to confuse. Its alternate leaves, in groups of three leaflets or rarely 5, 7, or 9, while other toxicodendrons always have only three leaflets. Each leaflet can measure up to 4 in (10 cm) long and has a glossy texture. The appearance of the leaves can vary greatly from one plant to another: scalloped, toothed, or lobed edges. In the fall, the leaves turn to orange or red, like other toxicodendrons.

Western poison oak shrub at fall.
Western poison oak shrub at fall.

Trunk and stems

The color of the stems and trunk is a grayish brown. Under good conditions in open sunlight, it grows as a dense shrub with a trunk up to 8 in (20 cm) diameter. Often, it can grow as a 3 to 4 feet (1.25 m) high bush. In shaded areas it grows as a climbing vine. With its climber variety, it generates fine aerial roots that allow it to cling to the bark and climb on trees.

Western Poison Oak (T. diversilobum) as a climbing vine.
Western Poison Oak (T. diversilobum) as a climbing vine.
Western poison oak (T. diversilobum) shrub. Source: Bri Weldon on Flicker
Western poison oak (T. diversilobum) shrub. Source: Bri Weldon on Flicker

Flowers and fruits

The flowers in clusters, at the base of the stems, are pale, yellow green. These flowers are very small, often only half an inch (1 cm) in diameter and appear all throughout spring (April – May). The fruit is small, round, striped (like a pumpkin), and yellowish or greenish. The fruits come in drupes near the flowers, at the base of the stems, and appear in late summer.

Western poison oak flowering. Source: Eeekster
Western poison oak flowering. Source: Eeekster
Western poison oak (T. diversilobum) fruits. Source: Noah Elhardt
Western poison oak (T. diversilobum) fruits. Source: Noah Elhardt

Propagation

This vigorous plant is propagated by its seeds, located within fruit. The fruit can drop near the plant or birds can eat the fruit and expel the seeds later in their droppings. Another plant can then push into this place, if the germination is done correctly. Also, the plant spreads using its horizontal rootstocks (rhizomes), which are stem tissue. A root system can cover several feet in diameter.

Habitat and distribution

Western poison oak is adapted to a great range of environments like moist evergreen forest, woodlands, dry chaparral and by rivers and creeks. It grows in many different soils but seems to prefer sunny places, clear and not too dry. This toxicodendron is located along the Pacific coast from Vancouver, including southern Vancouver Island in a few remote areas to the Baja California peninsula. Note that where western poison oak grows, in western British Columbia and the northwestern United States, western poison ivy is absent.

Western poison oak habitat area (Toxicodendron diversilobum).
Western poison oak habitat area (Toxicodendron diversilobum).

Videos about Western poison oak

Northern California Bushcraft series – Poison Oak Identification
Western Poison Oak Slideshow
Western Poison Oak, Toxicodendron diversilobum, San Diego, California
Poison Oak (Toxicodendron diversilobum)
Poison Oak – Poison Ivy – Outdoor Tips
This Is Poison Oak
Pacific poison oak biological warfare (enough urushiol to infect everybody on the planet)

Resources about Western poison oak

Similar plants looking like Poison oak

White oak

Botanical name: Quercus alba.
A new white oak sprout or a young white oak shrub under 2 feet (60 cm) high may be confused with eastern poison oak and western poison oak. Pay attention. The poison oaks always have 3 leaflets by leaf and the leaflet edge is much less twisting than the white oak.

White oak, young leaves.
White oak, young leaves.

More about White oak:

Red Oak vs White Oak

Fragrant Sumac

Botanical name: Rhus aromatica.
Fragrant sumac is a shrub that can grow up to 2 meters tall and it inhabits mostly uplands areas. It produces yellow flowers in clusters in spring. Its hairy red drupes of fruits are bigger than on poison oaks. Like  poison oaks, the leaves are made of 3 leaflets. One thing is particular to fragrant sumac: the 3 leaflets join the stem at the same point. Pay attention! On poison oaks the ending leaflet is shifted from the other 2 leaflets. The other thing particular to fragrant sumac: the flowers and fruits grow at the end of a short “pine cone like” bud. The leaves and stems of fragrant sumac have a citrus fragrance when crushed, unlike poison oaks.

Fragrant Sumac, leaves and buds, by Bruce Marlin.
Fragrant Sumac, leaves and buds, by Bruce Marlin.
Fragrant sumac, fruits, by EnviroRunner on Flickr
Fragrant sumac, fruits, by EnviroRunner on Flickr

More about Fragrant sumac: