Answer: Poison ivy, western poison oak, and poison sumac have the poisonous sap (urushiol) in their roots, stems, leaves and fruit. The sap is released when the plant is bruised, making it easier to contract Rhus-dermatitis in the spring and early summer when leaves are tender. The sap may be deposited on the skin by direct contact with the plant or by contact with contaminated objects, such as shoes, clothing, tools and animals. Severe cases have occurred from sap-coated soot in the smoke of burning plants. Because urushiol is inside the plant, brushing against an intact plant will not cause a reaction.
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