By Patsy Cotterill
Western poison ivy (Toxicodendron radicans var. rydbergii) and wild sarsaparilla (Aralia nudicaulis) are both native to the Edmonton area. These two plants have obvious similarities but should be carefully distinguished because poison ivy can cause a nasty case of dermatitis if cut surfaces of the plant come in contact with skin. Fortunately, there are plenty of differences between these two species, allowing for correct identification.
Wild sarsaparilla (Aralia nudicaulis) is an extremely common plant throughout the wooded areas of Alberta. It is rhizomatous and forms a tall-herb ground cover in woods, but does not form the compact patches like those of poison ivy. Its leaves are twice compound, consisting of three stalked divisions which are then further divided into five (occasionally three) leaflets. The leaflets are ovate-oblong to elliptic-lanceolate (narrower than those of poison ivy), pointed and toothed. The flowers are characteristic “balls” of greenish-white flowers on separate stalks from the leaves, and the fruits are loose clusters of blackish “berries.”
Western poison ivy (Toxicodendron radicans var. rydbergii) is much less common, with a scattered distribution in Alberta which, I speculate, may have something to do with accidental human introduction. It occurs in more open areas than wild sarsaparilla, and is often associated with water (on well-drained soils), although it can also occur in open woods. Several populations are established in Edmonton’s river valley system and in a Devon ravine. It forms dense patches by means of runners (stolons). The leaves are singly compound, divided into just three leaflets which are ovate or rhombic-ovate (so wider than those of wild sarsaparilla), and irregularly toothed or not toothed. The dense clusters of white flowers forming similar clusters of white, smooth fruits, do not seem to occur commonly among local populations.
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