According to the signboard at Jinshagou Nature Reserve, this ancient fern has "kind of medicinal functions of curing bleeding wound, fire wound, scald, furuncle, carbuncle and mumps."
very wet, subtropical valley
I spotted this at Jinshagou Nature Reserve. It wasn't a very popular reserve for foreigners. I had the whole place to myself when I visited in the beginning of winter but surprisingly, they had signboards with english on them and they were fairly informative.