Plant Diversity

Tracheophytes— Flowering Plants (Angiosperms)

What is the difference between poison ivy, oak, and sumac?

These North American woody plants grow in almost any habitat and are quite similar in appearance. Each variety of plant has three-leaf compounds that alternate berrylike fruits and rusty brown stems. Poison ivy (Rhus radicans) grows like a vine rather than a shrub and can grow very high, covering tall, stationary items such as trees. The fruit of R. radicans is gray in color and is without “hair,” and the leaves of the plant are slightly lobed. Rhus toxicodendron, commonly known as poison oak, usually grows as a shrub, but it can also climb. Its leaflets are lobed and resemble the leaves of oak trees, and its fruit is hairy. Poison sumac (Rhus vernix) grows only in acidic, wet swamps of North America. This shrub can grow as high as 12 feet (3.6 meters). The fruit it produces hangs in a cluster and ranges from gray to brown in color. Poison sumac has dark-green leaves that are sharply pointed, compound, and alternating; it also has inconspicuous flowers that are yellowish green. All parts of poison ivy, poison oak, and poison sumac can cause serious dermatitis.


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