Tuesday, March 06, 2012

Northeast Illinois Invasive Plant Partnership Invasive Plant of the Month

In honor of the Irish, the Air Potato (or Chinese Yam) is our invasive plant of the month. There are no known populations in the Chicago area, but Southern Illinois has several documented populations. For this reason, it is can be found on the New Invaders Watch List.

Dioscorea oppositifolia is a perennial vine that is native to China. It may climb as high as 16 feet along tree trunks and branches, produces small yellowish-white, cinnamon-scented flowers in its leaf axils in late spring-early summer, and in late summer-early fall it produces bulbils (that really look like little potatoes) in its leaf axils. It grows quickly and can outshade and displace native plants.

D. oppositifolia does have a native look-alike in Dioscorea villosa. D. oppositifolia leaves have a heart-shaped base with a deep notch and veins that widen their distance from each other as they approach the edges of the leaf. In addition, the base of the leaf (where the petiole joins) and the top of the petiole are purple colored (more visible from the underside of the leaf). D. villosa leaves are heart-shaped without a notch and the veins curve out and then in toward the tip of the leaf. Additional information about this invader can be found Northeast Illinois Invasive Plant Partnership website.


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