Where I grew up in New York, if you were a kid who liked to play outdoors, you were aware of Poison Ivy. Either you or someone you knew had dealt with the itchy rash symptoms that come from accidentally brushing into it. Poison Ivy is the weed that no one wants, not that anyone wants weeds on their property. There is a common rhyme to help identify and avoid an encounter, ‘leaflets of three, let it be”. Unfortunately it is native throughout the United States and much of Southern Canada in variety of habitats including wet or dry woodlands, thicket valleys, clearings, fencerows, roadsides, and waste grounds. It can thrive in disturbed areas. It mainly appears as a bushy, erect or trailing shrub or as a woody climbing vine. The rhyme comes from the stems which have leaflets of three that are smoothed or toothed, rounded or pointed, glossy or dull.
All the parts of the plant contain a toxin plant oil called urushiol which can cause significant short and long lasting skin irritations (allergic dermatitis) in most human beings. The infections can occur from direct contact with the plant, indirect contact, or from breathing smoke from a fire of the plant material. Luckily some humans are immune, and I am one of them!