"welts and sores on his arms and hands of the sort that poison ivy or poison oak can give"
Poison Ivy
Public DomainPoison Ivy
Poison oak
Public DomainPoison oak
Welts from contact with poison ivy
Public DomainWelts from contact with poison ivy

Poison ivy and poison oak are two plant species that release urushiol, an oily substance that causes a skin rash when touched.


You can learn more about them from the Poison Ivy, Oak, & Sumac Information Center.