barkdust

seems to be generally a northwest thing, since that's where the trees used to make it grow natively, which is probably why you've never heard of it.

it's a form of mulch, only instead of being a mishmash of all sorts of parts of trees and other things, it's made from just the bark, and shredded like pulled-pork bbq, which makes it different from bark chips, which are just chips of bark (duh). bark chips are, thusly, different from wood chips, in that they are just made of the bark of the tree, not the meat of the tree (again, duh).