Poison-Sumac
Common Names:
Poison-sumac, Swamp-sumac, Poison-dogwood, Poison-elderberry
Scientific Name:
Toxicodendron vernix (L.) Kuntze
(syn. Rhus vernix L.)
Family:
Anacardiaceae (Cashew Family)
Native Range:
Rare in Canada; occurs in southern Ontario and Quebec.
Toxicity:
Oils in leaves, stems, and roots can cause severe skin rash (contact dermatitis). Smoke from burning plants is intensely irritating to skin, eyes, and lungs.
Size & Growth
Height: Up to 6 m
Trunk Diameter: Up to 10 cm
Form: Shrub or very small tree; crown small, rounded; trunk slender with little taper
Leaves
Type: Deciduous, alternate, pinnately compound
Leaflets: 7–13 per leaf, 4–8 cm long, long-pointed, wedge-shaped base, smooth margins, stalked
Color: Lustrous dark green above, whitish and hairless beneath
Stalk: Often red
Quick Recognition:
Leaflets curved, 7–11 (sometimes up to 13)
Terminal bud dark yellow, granular, with non-overlapping scales
Twigs & Buds
Twigs: Slender, drooping; dark green and hairy when young, mottle to brownish-yellow and hairless with age; prominent lenticels
Terminal Bud: Conical, 10–19 mm long, several purplish-brown scales
Lateral Buds: Smaller
Leaf Scars: Broad, shield-shaped, dot-like vein scars in 3 groups
Flowers & Fruit
Flowers: Small, yellow, in drooping branched clusters in leaf axils
Pollination: Pollen drops just before opening
Fruit:
Rounded, glossy white or ivory, 1-seeded, thin-fleshed
10–13 mm across
In loose, drooping clusters, often persisting through winter
Fruit husk with 4 ridges extending below sharp tip; kernel bitter
Bark & Wood
Bark: Light gray, smooth; tight with shallow fissures; young bark shows irregular vertical lines
Wood: Shrubby, small, not commercially used
Habitat
Open, swampy woodlands
Often mixed with willows, black ash, white elm, silver maple, eastern white-cedar
Prefers wet lowland sites
Management & Cautions
Avoid contact with leaves, stems, and roots
Protective clothing recommended during handling
Burning the plant is highly hazardous
Can spread via root sprouts
Fun Facts / Notes
Black spot test: crush a leaf on white paper; juice turns brown then black in ~24 hours
Only poison-sumac species in Canada that reaches tree size
Closely related to poison-ivy and poison-oak.
Why? How? Here's a summary ChatGPT put together for me:
Sassafras and poison-sumac are both part of the same plant “extended family” of flowering plants, but in different actual families—sassafras is in the laurel family (Lauraceae), while poison-sumac is in the cashew family (Anacardiaceae). They’re related because both produce aromatic oils and chemicals that affect humans or wildlife, and both are woody plants that grow as shrubs or trees. Basically, they’re cousins in the plant world who happen to share some traits, like scented leaves and important ecological roles, even though their exact lineages split long ago.