I did not fall, but collecting insects once in the rainforest I brushed my pant-leg against this. Couldn't understand the pain. Was dumb and naive to not read

I did not fall, but collecting insects once in the rainforest I brushed my pant-leg against this. Couldn't understand the pain. Was dumb and naive to not read the local park brochure when we came in, only when we left after the first day of work. When I went back to collect the traps I realized I had placed them all along a huge fallen tree, with this plant running right beside it. I was incredibly lucky. Stung for around 4 days IIRC, and this was super minor contact from what I could tell. I had been hyper aware of snakes etc., and well covered for other biting insects, but my "adventure" pants seemed just a little too thin for coverage.