It will soon be summertime, and our summer interns will hit the woods, surveying sample plots and gathering data. Lesson number one: know what poison ivy looks like, avoid it if possible, and wash off well when you come in from the field. Poison ivy, Toxicodendron radicans, does have three leaflets per leaf. It commonly runs along the ground, and when it hits a tree, it climbs. Poison ivy, like English ivy, uses adventitious roots to cling to tree trunks to climb.
Look-alike Virginia creeper, Parthenocissus quinquefolia, which has five leaflets per leaf, has no such roots along the vine. And neither do our woodland grapes — notice the dark brown grapevine in the photo with the Virginia creeper.