When in the great outdoors, nature is bound to come calling, so what are some good natural toilet paper substitutes when the real thing isn't available?
- Smooth oval rocks (from river beds if possible)
- Rounded sticks
- Leaves (as said elsewhere, be careful of which kinds)
- soft pine cones (relatively rare, but plentiful where they exist!)
- handful of grass
- Carry a piece of cloth specifically designed for this purpose and be sure to do two more things: 1 - Don't use the cloth for anything else, and 2 - Wash it clean as regularly as possible.
Species in the forest will vary by locale. Here in the Pacific Northwest, Thimbleberry aka Salmonberry leaves are thick and soft, so they make a good wiping implement.
The subtly-named How to Shit in the Woods is a good primer on this topic. One option described there is to use urine. Basically, you hold back the urine until you're done with the bowel movement, then use the pee to wash up.
To clean your hands afterwards, cedar can help. Take a bite of cedar scales (leaves) straight from a tree. Chew it up & mix with saliva. Spit it out on to your hands and rub all over.
In short, leaves. But as per the comment, make sure it's nothing that's going to cause skin irritations!
Also worth mentioning along the same lines that when doing your business, be sensitive in where you do it - not near bodies of water people might drink from for instance.
Water is also an option, especially if there are no leaves of desirable properties. Deeper puddles, streams, etc. (That you should think twice about consequences for other people goes without saying.)
You can carry an empty water bottle for this purpose, fill it up in some stream when you know you have to go in a while and wash up like in many Asian countries. I wouldn't recommend doing it in the stream itself for hygienic reasons, plus using a bottle is also a lot easier when you're used to it. I can refer you to this other stackexchange site: https://travel.stackexchange.com/questions/3080/ok-were-all-adults-here-so-really-how-on-earth-should-i-use-a-squat-toilet
Compressed toilet paper coins. These are made of plant cellulose and are biodegradable. Just add about a teaspoon of water or less and they unfold into the most comfortable toilet paper you can imagine. They are about the size of a stack of five US nickles each and are strong enough for washing off your face or other areas. Strict places like the AppTrail you can not use these but other places these are just fine just treat them like TP and bury it.
You will find many of the smaller palm trees have a soft inner fiber if split open & dug out with a flat stick. Or coconut fiber removed from green coconuts. Some like silk. Leaves I do not use most have a sharp edge to them so does grass. Just split them open remove soft fibers wad them up & use. Will be slightly damp. Often better than toiletpaper. A squat in the river is not bad use left hand to clean.