I recently got a firebowl for backyard s'mores making and fire building practice. I too am concerned with things like this because thus far I have not been able to start a fire using dry leaves and dry grass with a Magfire. I'm thinking that if I had to start a fire using only natural materials when the materials are the slightest bit damp, I'd be in big trouble!

In the "Prepared to Survive" DVD they suggest the splitting larger branches method to obtaining dry material. The dry stuff can be shaved and powdered to make nice tinder and kindling from what I understand.