If you hang around GMARA events you’re guaranteed to hear volunteers joking about nettles. Not sure what a nettle is? Time to “brush up” on your knowledge! (ha ha)
See those tiny white spines on that leaf?
Wikipedia says that nettles have “many hollow stinging hairs on the leaves and stems which act like hypodermic needles, injecting histamine and other chemicals that produce a stinging sensation.”
You’ll find patches in areas where the ground stays wet but the sun can peek through.
They almost always grow right in the middle of the route you’re trying to follow, too.