Poison ivy (formerly Rhus radicans now Toxicodendron radicans)
Can you identify poison ivy if you should come across this plant while weeding in your garden or out hiking? This is a vital skill if you wish to avoid the rash and irritation that results from coming in contact with it. The old adage: “Leaves of three, let it be!” is a wise approach when anywhere near poison ivy.
Poison ivy has three separate growth forms. Most commonly on the home grounds it will take the form of an erect woody shrub or a trailing plant that creeps along the ground. It can also be a woody vine that will climb trees. When poison ivy grows on trees, or even telephone poles, it produces aerial roots all along the stem that give this climbing vine form the appearance of a fuzzy rope.
The leaves of poison ivy also vary. Though it is always a compound leaf with three leaflets, the leaf margins may be toothed, lobed or smooth. Leaf sizes may vary but the middle leaflet, which is on a long stalk is somewhat larger than the other two which are more closely attached to the leaf stem (petiole).
Control of poison ivy can take various forms. It can be pulled out by hand, spraying the plants with an herbicide or cutting the stem (on vines) and then treating the cut stem and regrowth with herbicide. Check with your local nurseryman or garden center for the most recent recommendations for chemical control. In all cases be extremely cautious. Do not have any direct skin contact with the leaves or stems which contain the toxic oil urushiol. More information about this toxin can be found at http://www.eoearth.org/view/article/171613/ .
Photos courtesy of Wikipedia and About.com.