Also known as Central poison ivy or Climbing poison ivy;
Often called only Poison ivy, its botanical name is Toxicodendron radicans. Six subspecies of the T. radicans exist (divaricatum, eximium, negundo, pubens, radicans, verrucosum) but I will not dwell on these subjects. Discovered by the first settlers, Eastern poison ivy is present in the eastern United States. This species of toxicodendron generates fine aerial roots that allow the plant to cling to the bark of trees and rise up to the top of them. That’s the major difference between Eastern and Western poison ivy. Also, “radicans” means “having rooting stems.” The Eastern poison ivy can be a climbing or crawling vine or be a shrub. The Western poison ivy (Rydberg) only crawls. Some still consider the Western poison ivy as a subspecies of the Eastern poison ivy.
The saying “Leaves of three, let it be. Leaves of five let it thrive.” teaches us to beware of a plant that has three leaves. That is the case with the two poison ivies, and the two poison oaks. The leaf is a group of three leaflets at the end of a stem (petiole), which links the trunk. The central leaflet, pointing outward, has a longer stalk than the two others. The leaflets are egg-shaped ending in a point. The edges can be smooth, toothed or wavy. The leaves length can also vary greatly depending on the maturity of the plant, the soil type and the region. The leaves have a glossy (polished appearance) reddish in spring, green in summer and take different shades of yellow, orange, red or bronze in the fall.
Trunk and stems
Eastern poison ivy is a woody plant that climbs on trees, posts and anything vertical. Eastern poison ivy is a vine that goes up and, sometimes, a shrub. We can easily recognize the climbing Eastern poison ivy by the fine aerial roots that allow the plant to cling to the bark of trees. With all these fine roots, the trunk can sometimes look like a tousled old rope. The texture of the trunk is always slick with a grey-brown color. As the plant become stronger and the trunk wider, the plant can spread laterally to 8 feet or more from the trunk to reach sunlight. The trunk and stem, like all parts of this plant may cause skin irritation if broken and if the urushiol break out.
Flowers and fruits
In June and July, some plants produce beige to yellow-green discrete flowers. These flowers are sometimes hidden by the leaves and hard to see. In late spring, beige round fruits with 1/8 to 1/4 in (3-7 mm) diameter, appear in clusters.
This vigorous plant is propagated by its seeds, located within fruit. The fruit can drop near the plant or birds can eat the fruit and expel the seeds later in their droppings. Another plant can then push in this place, if the germination is done correctly. The poison ivy also spreads by suckering from its long root system located at the surface or just below the ground.
Habitat and distribution
Eastern poison ivy is present in the eastern half of United States, up to the southern Ontario, Canada. If this variety of poison ivy is absent north of these regions is because its long aerial stems cannot withstand harsh winters.
You can find eastern poison ivy in various types of soils, in sunny or partial shade, wetlands, dry, sandy or rocky, on the edge of fields, roads, railways, rivers. The place where the plant is established is often densely settled and is spreading rapidly in deforested and disturbed lands. This plant can grow well where many other plants can not, such as dry, rocky and acid soils. Always keep your eyes open.
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