Ontario Weeds: Poison sumac
Table of Contents
- Name
- Other Names
- Family
- General Description
- Stems and Roots
- Leaves
- Flowers and Fruit
- Habitat
- Similar Species
- Caution
- Related Links
Name: Poison sumac, Rhus vernix
L.
Other Names: sumac à vernis,
Poison elder, Poison dogwood, bois chandelle
Family: Cashew Family (Anacardiaceae)
General Description: Coarse shrub
or small tree 1.5-7m (5-23ft) high, often branched at the base,
with brown to gray smoothish bark;
Photos and Pictures
Poison sumac. End portion fo a twig with 2 compound
leaves and 2 clusters of small white berries.
Stems & Roots: Branches hairless,
very slightly roughened with tiny, wart-like surface glands, and
bearing prominent leaf scars.
Leaves: Leaves alternate on the branches,
but each leaf pinnately compound with 3 to 6 pairs of leaflets that
are nearly opposite each other, plus 1 terminal leaflet; each leaflet
4-10cm (1½-4in.) long and ½ to 2/3 as wide, somewhat
rounded at the base and pointed (acuminate) at the tip, dark green
above and lighter green below; margins of leaflets are usually smooth
but occasionally may be wavy, irregularly lobed or coarsely toothed;
the whole compound leaf (7-13 leaflets plus their central stalk)
falling from the branch in autumn.
Flowers & Fruit: Flowers dull
white, produced in 4-20cm (1½-8in.) long, spreading or pendulous
panicle-like clusters that arise from leaf axils; berries whitish
or drab, 4-5mm (1/6-1/5in.) long. Flowers in July.
Habitat: Poison sumac is found in
southern Ontario in wet woods and edges of swamps and lakes.
Similar Species: Poison sumac is distinguished
by its appearance as a coarse shrub or small tree, its alternately
arranged, pinnately compound leaves with 7-13 usually smooth-margined
leaflets and its clusters of white flowers followed by whitish berries.
Prickly-ash and the true Ash trees, Fraxinus spp., [frêne]
also have pinnately compound leaves with smooth margins on their
leaflets, but Prickly-ash has pairs of large prickles along its
branches and smaller ones at the bases of some of the leaflets,
and the true Ash trees have their compound leaves in opposite pairs
along the branches. Staghorn sumac, Rhus typhina L.,
[RHUTY, sumac vinaigrier, sumac amarante, vinaigrier], a very common
shrub with velvety-hairy branches (hence its common name), sharply
and coarsely toothed leaflets in pinnately compound leaves that
turn vivid red in fall, and cone-shaped clusters of red fruits is
not poisonous.
Caution: The entire plant
is as poisonous to most people as is Poison-ivy. Because both the
foliage in summer and the bare twigs in winter can cause severe
dermatitis, take special care to avoid these parts touching hands
or face when in damp woods.
Related Links
... on general Weed
topics
... on weed identification, order OMAFRA
Publication 505: Ontario Weeds
... on weed control, order OMAFRA
Publication 75: Guide To Weed Control
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