Poison Plants
Toxicodendron radicans (Poison ivy; older synonyms Rhus toxicodendron, Rhus radicans[1]) is a plant in the family Anacardiaceae. The name is sometimes spelled "Poison-ivy" in an attempt to indicate that the plant is not a true Ivy (Hedera). It is a woody vine that is well known for its ability to produce urushiol, a skin irritant that causes an itching rash for most people, technically known as urushiol-induced contact dermatitis.
Habitat and range
Poison Ivy grows throughout much of North America, including all Canadian provinces except Newfoundland (and the Territories) and all U.S. states except Alaska, Hawai‘i, and California (which instead houses Poison-Oak, a very similar plant), as well as in the mountainous areas of Mexico up to around 1,500 m (4,900 ft) (see caquistle or caxuistle—the Nahua term), and is normally found in wooded areas, especially along edge areas. It also grows in exposed rocky areas and in open fields and disturbed areas. It also grows as a forest understory plant, although it is only somewhat shade tolerant.[1] The plant is extremely common in suburban and exurban areas of New England, the Mid-Atlantic, and Southeastern United States. It rarely grows at altitudes above 1,500 m (4,900 ft), although the altitude limit varies in different locations.[1] The plants can grow as a shrub up to about 1.2 metres (3.9 ft) tall, as a groundcover 10–25 cm (3.9–9.8 in) high, or as a climbing vine on various supports. Older vines on substantial supports send out lateral branches that may at first be mistaken for tree limbs.
It is not particularly sensitive to soil moisture, although it does not grow in desert or arid conditions. It grows in a wide variety of soil types, and soil pH from 6.0 (acidic) to 7.9 (moderately alkaline). It can grow in areas subject to seasonal flooding or brackish water.[1]
It is more common now than when Europeans first entered North America. Real estate development adjacent to wild, undeveloped land has engendered "edge effects," enabling poison ivy to form vast, lush colonies in such places. It is listed as a noxious weed in the U.S. states of Minnesota and Michigan and the Canadian province of Ontario.