A sign of things to come ...
AKA 'Tree Nettle'. I brushed against some of this in the Port Hills above Christchurch. Googled it after the tingling persisted for three days. It's certainly pretty potent. Can't help wondering what evolutionary purpose the poison has. To keep the Moa off?
For the newbie to onga-onga, contacting this stuff is painful. People are affected differently but contact will cause extreme pain.
On a tramp, a mate slipped and pressed his palm into one leaf - instant intense pain diminishing, after 2 hours, to a level that could not be ignored - lasting for 2 days.
Four days later, he had a delayed reaction - paralysis of the whole arm, blurred vision and associated pain for about 15 minutes - scared the willies out of him.
A sufficient dose of the onga-onga neuro-toxin can kill - so, BE CAREFUL.