How long is all parts of Poison Ivy considered poisonous?

Poison Ivy is considered poisonous year-round because all parts of the plant—leaves, stems, and roots—contain an oil called urushiol that can cause allergic skin reactions in humans. This oil does not degrade with seasonal changes and remains active even when the plant is dormant, such as during winter months. The potential for exposure exists at any time of the year, making it crucial for individuals to recognize and avoid contact with the plant regardless of the season.

In contrast, some of the other options suggest limited times or conditions when the plant is poisonous, but those do not account for the continuous presence of urushiol and its ability to cause reactions at any point throughout the year. Understanding this property of poison ivy helps individuals manage risk effectively by being continually aware of their surroundings.