Anacardiaceae: Toxicodendron rydbergii

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Family Name

Anacardiaceae

Common Name

Poison ivy

Native American Name

Lakota: wikȟóška pȟežúta

Description

Toxicodendron rydbergii is a perennial shrub or subshrub with simple, unbranched stems 0.3-2 m in height and growing from branched subterranean stolons that often form thickets. Leaves are compound ternate, often drooping, each group of 3 at the end of a long stalk alternately attached to the woody main stem. Leaflets are up to 16 cm long and 11 cm wide, the center leaflet ovate to rhomboid, pointed at the tip and rounded or tapering at the base with toothed margins. The 2 lateral leaflets sessile or with short petioles and asymmetrical in shape, toothless or having a few large teeth, sometimes just on one side. The upper leaf surface is hairless and shiny, becoming dull with age; the underside is lighter in color with a few hairs along the midvein. Flowers are in small, paniculate clusters that arise from the leaf axils. Each small flower 1-3 mm across, has 5 sepals that are fused and green below and cream colored and free above. The 5 petals are cream colored with purplish veins and yellow stamens are usually visible. The fruit is a whit to yellowish globose drupe 4-7 mm in diameter that often persist into the next year. Poison ivy blooms in May and June and sometimes again later in the summer. Plants are found on prairie hillsides, stream banks, flood plains, roadsides and open woodlands throughout South Dakota.

Additional Notes

Poison ivy can be very toxic, touching or merely brushing against it can result in painful swelling, itching, blisters, or a rash in susceptible people. A similar species, Toxicodendron radicans (eastern poison ivy), also occurs in South Dakota and differs from T. rydbergii in being a trailing or climbing vine.

Horticulture Notes

Not suitable for cultivation.