Some elves will completely eschew any connections with society, be it their own or those of other races, and retreat to the wilderness to meditate and serve nature in isolation. Following several decades of such service, an elf may go beyond merely reflecting its environment and actually become one with it.
These former elves, now embraced and blessed by the land itself, change radically in physiology and appearance to become Wilden. Their pasts fade into the background of their minds, and while some hang onto some choice memories and elements of their former identities, most embrace their new lives and callings as a clean slate.
Outlined in PHB3, I thought these guys were neat, but I’d still like to be consulted first if you want to create a Wilden character.