writing on a leaf?

I want to thank you all for maintaining this forum. It is a valuable
resource.

I have read that early Pali texts were written on leaves but I am
having trouble understanding this. How do you make a clear
mark on a leaf, and how long does a leaf remain readable?
What kind of leaves are used -- large leaves such as banana?

(I do not plan to write on leaves, myself. I just want to understand
how it was done.)