Poison sumac

About

A native shrub or small tree of eastern swamps and bogs that can cause a severe rash. It breaks the 'leaves of three' rule, so people often don't recognize it.

Also called swamp sumac, thunderwood

How to identify it

Look for

Each leaf has 7 to 13 smooth-edged leaflets set in pairs along a bright red stalk. It grows up to about 20 feet tall with smooth gray-brown bark. Loose, drooping clusters of pale, whitish berries hang on through winter.

Look-alikes

Harmless smooth sumac has 11 to 31 toothed leaflets, and winged sumac has leafy wings along the leaf stalk; poison sumac has 7 to 13 smooth-edged leaflets on a red stalk and drooping whitish fruit. Young ash trees and poison ivy are also confused with it.

Where it grows

Wet, acidic ground: swamps, bogs, marshes and thickets along rivers.

When

Leaves appear in spring, greenish flowers hang in early to mid summer, and the whitish berries ripen in late summer and stay into winter.

How it spreads

Birds eat the berries and carry the seeds.

Most common in

What to do, gentlest first

Protect yourself first. Weed killers are a last step; always read and follow the label.

1. Learn it and give it room Prevent

   Learn the red-stalked leaf with 7 to 13 leaflets before working in wet ground. Wear gloves, long sleeves, long pants and eye protection.

   Wash tools and clothes after contact; the oil lasts on surfaces.

2. Cut or dig small plants with care By hand

   Small plants can be cut or dug out, best in winter when there is less sap.

   Bag the pieces for the trash and never burn them. Call a professional for shrubs and small trees.

3. Spot-treat with glyphosate or triclopyr Conventional spray

   Spot-spray or treat freshly cut stumps while the plant is growing; repeat as needed.

   Read and follow the label. Many lawn and brush herbicides also kill garden plants, so keep spray and drift off anything you want to keep. In wetlands, use only products labeled for use near water.

Uses, wildlife and pets

For wildlife

Bees visit the flowers, and birds such as grouse, pheasants and bobwhites eat the fruit.

Pets

The ASPCA lists poison sumac as non-toxic to dogs, cats and horses, but pets can carry the oil on their fur to people. Bathe a pet that brushed through it while wearing gloves.