I'd use leaves or even the shirt off my back if I had to; I don't walk around in stinky or sticky pants.
Before the days of Toilet paper, a goose's neck was considered the ultimate luxury for this purpose. <br />
Seriously, I kid you not.
Corn cobs, too, eh?
Or you could wait 'til you get home then use a cheese grater.
Or a sock maybe...lol
You really want to know? ... I'd take off my undies and use those, then burn them. I wouldn't chance a rash from an unforgiving plant species.