Although you must beware whenever you enter a weedy patch, lest poison ivy be lurking within (amongst other weeds), the itchy vine often announces its presence with a louder statement, as the dominant plant....
Photo of leaves of mature plants.
This picture of poison ivy shows what the plants look like once they've matured. The leaves are green, and the plants are about two feet high. Poison ivy vines often grow en masse, as in this picture, thereby "taking over" an area and becoming the dominant plant.