Pfftt your poison ivy is a limp wristed weak little plant...
I present to you Onga Onga - a native NZ plant that carries a standard nettle poison plus another nasty poison (possibly a neurotoxin). It kills horses, dogs, stock, one person has been recorded as dying from it. I 'brushed' it once with a finger, only lightly, I after the burning sensation stopped I lost feeling in that finger for about a week.
The stinging hairs are very obvious on this nettle being some 6mm or more in length. Crowe describes them as being like a hypodermic syringe. “The slightest touch knocks off the tip of the needle leaving a slanting point that drives into the skin. The elastic barrel at the base of the needle immediately shrinks, pumping its venom into the victom. The extract from just one of these long, fat stinging hairs is sufficient to kill a guinea pig.”
Ongaonga contains the same poison as common garden nettle but also has another, as yet unidentified, poison. In severe cases of poisoning artificial respiration and injection of atropine may be necessary. Pain can be eased somewhat with calamine or antihistimine medication. Common along edges of forest (including forest tracks!) and regenerating scrub.
This photograph taken on Kapiti Island.