Toxicondendron radicans
A poisonous flowering perennial plant distributed widely across the United States known for causing an itching, irritating and often painful rash on most people who come into direct contact with it. This reaction is caused by urushiol, a compound in the sap that helps the plant retain water. This compound can persist on clothing, plants, and other surfaces for several years, so it is important to wash anything that comes into contact with poison ivy in order to avoid future exposure. The entire plant, not just the leaves, is poisonous.
Though highly variable in appearance, poison ivy is commonly identified by three droopy, almond-shaped leaves. Leaf colors vary from light to dark green and turn reddish in the fall. Younger leaves in the spring are typically red before turning green. All plant variations have smooth woody stems, but can grow as a trailing vine 10-25 centimeters tall, a shrub up to 3 feet in height, or as a climbing vine that grows on a tree or some other type of support. Flowering occurs from May through July. The flowers range in color from yellow to white. Small, gray-white and berry-like fruits appear fro August through November.
Poison Ivy is typically found in wooded areas with partial sunlight, older suburban developments, and can grow in exposed rocky areas, and open fields.
Similar species: box-elder, Virginia creeper, tree of heaven seedling, Sassafras seedling, raspberry, jewelweed
Pastinaca sativa
A poisonous perennial herbaceous plant native to Eurasia, wild parsnip is phytophototoxic and can cause rash, blistering and discolored skin in the presence of sunlight. Though grown as a root vegetable, it is considered a noxious weed in several states and in some instances, prohibited from transportation
Wild parsnip is monocarpic and thus spends one or more years in a smaller 6 inch tall rosette stage before entering a 4 foot tall flowering stage. The plant dies after flowering and producing seed. The leaves are alternately arranged and consist of 5-15 egg-shaped leaflets along both sides of a stalk. Leaflets can be sharply-toothed or lobed at the margins. The five-petaled, yellow flowers bloom in June throughout the summer.
Wild parsnip is a widespread colonizer of dry, mesic, and wet disturbed and open areas. It is common along roadsides, railways, and oak openings.
Similar species: Golden Alexander, Cow parsnip, Poison hemlock
Laportea canadensis and Urtica dioca
Stinging nettle and wood nettle have several tiny stinging hairs on their leaves and stem. Direct contact with both types of nettles results in a brief, but intense itching of the skin. Both are similar in size and appearance, reaching heights of 2-7 feet with slender stems and coarsely serrated leaves. A difference occurs in leaf arrangement as the wood nettle has an alternately arranged leaf pattern whereas the stinging nettle's are oppositely arranged.
Though both plants are widespread, their habitats differ with the wood nettle perhaps being of more concern for responders to inland river spills. The wood nettle grows in dense stands in deep-shaded, moist woodlands or underneath trees found along streams or lakes. The stinging nettle is more common on higher ground in full sunlight.
Similar species: Jewelweed, Slender nettle, False nettle, Clearweed, Mint, Raspberry
Heracleum mantegazzianum
A plant of considerable stature. the giant hogweed is difficult to miss. It has a stiff, bright green stem spotted with dark red and hollow red-spotted leaf stalks that produce bristles. The compound leaves are sharply incised and can grow up to 3-5 feet in width. The large white inflorescences typically flower from mid-June to mid-July. Its height ranges from 6-18 feet. Like the wild parsnip, giant hogweed is phytophototoxic. Direct contact with the sap combined with exposure to sunlight will result in blisters, burns, long-lasting scars, and-if exposed to eyes-blindness. Moreover, skin will continue to burn for up to two years upon repeated exposure to sunlight. These reactions can result from contact with the leaves, roots, stems, flowers, and seeds of the plant.
Giant hogweed distribution is limited to the Northeast and Northwest United States, Illinois, Michigan, and Wisconsin. It prefers to grow along riverbanks, making it a concern for responders to inland river spills.
Similar species: Common hogweed, Cow parsnip, Queen Anne's Lace, Elderberry