''Toxicodendron vernix'', commonly known as poison sumac, or swamp-sumach, is a woody

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

or small tree growing to tall. It was previously known as ''Rhus vernix''. This plant is also known as thunderwood, particularly where it occurs in the southern United States. Like its toxic relatives

poison ivy Poison ivy is a type of allergenic plant in the genus '' Toxicodendron'' native to Asia and North America. Formerly considered a single species, '' Toxicodendron radicans'', poison ivies are now generally treated as a complex of three separate s ...

and

poison oak Poison oak refers to two plant species in the genus '' Toxicodendron,'' both of which can cause skin irritation: *'' Toxicodendron diversilobum'' or Pacific poison oak, found in western North America *'' Toxicodendron pubescens'' or Atlantic po ...

, all parts of the plant contain a

resin A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Commo ...

called

urushiol Urushiol is an oily mixture of organic compounds with Allergic contact dermatitis, allergenic properties found in plants of the Family (biology), family Anacardiaceae, especially ''Toxicodendron'' ''spp.'' (e.g., poison oak, Toxicodendron vernic ...

, which causes skin and mucous membrane irritation to humans. When the plant is burned, inhalation of the smoke may cause the rash to appear on the lining of the lungs, causing extreme pain and possibly fatal respiratory difficulty.

Description

Poison sumac is a shrub or small tree, growing up to nearly in height. Each

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and ...

leaf has 7–13 leaflets, each of which is long. These are oval-to-oblong;

acuminate The following terms are used to describe leaf plant morphology, morphology in the description and taxonomy (biology), taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade ...

(tapering to a sharp point); cuneate (wedge-shaped) at the base; undulate (wavy-edged); with an underside that is

glabrous Glabrousness () is the technical term for a lack of hair, down, setae, trichomes, or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, ...

(hairless) or slightly pubescent (down-like hair) beneath. The stems along the leaflets are red and the leaves can have a reddish tint to them, particularly at the top of the plant. New bark for a poison sumac tree is lightish gray, and as the bark ages, it becomes darker. Its flowers are greenish, growing in loose axillary

panicle In botany, a panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a p ...

s (clusters) long. The fruits are subglobose (not quite spherical), whitish-gray, flattened, and about across; these are eaten by birds. Poison sumac fruit are creamy white and part of a cluster. Typically, they are around in size.

Distribution and habitat

Poison sumac grows exclusively in wet and clay soils, usually in

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

s and peat

bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and musk ...

s, in the eastern

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and extreme southeast

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

Ecology

The fruit and leaves of the poison sumac plant contain urushiol, an oil that causes an allergic rash upon contact with skin. They are, however, not toxic to birds or other animals, and eaten by them when other food is scarce, especially in winter.

Toxicity

In terms of its potential to cause urushiol-induced contact dermatitis, poison sumac is more toxic than its relatives

and

. The differences in toxicity in poison ivy, poison oak, and poison sumac are due to differences in the

side chain In organic chemistry and biochemistry, a side chain is a substituent, chemical group that is attached to a core part of the molecule called the "main chain" or backbone chain, backbone. The side chain is a hydrocarbon branching element of a mo ...

s of the chemicals in these plants. In general, poison ivy has a C₁₅ side chain, poison oak has a C₁₇ side chain and poison sumac has a C₁₃ side chain. The dermatitis shows itself in painful and long continued swellings and eruptions. In the worst case, smoke inhaled by burning poison sumac leads to life-threatening

pulmonary edema Pulmonary edema (British English: oedema), also known as pulmonary congestion, is excessive fluid accumulation in the tissue or air spaces (usually alveoli) of the lungs. This leads to impaired gas exchange, most often leading to shortness ...

whereby fluid enters the alveoli.

References

External links

Poison ivy / oak / sumac
in "The Medicinal Herb FAQ".
The Poison Sumac Page
��Photos and facts about poison sumac.

at ''Wayne's Word.''
Toxicodendron vernix
{{Authority control vernix Flora of Northern America