wall fern definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a small, hardy fern (Polypodium virginianum) of the most common family (Polypodiaceae) of ferns, with densely matted, creeping stems, found on cliffs and walls in E North America and often grown in gardens
wall fern definition by American Heritage Dictionary
A low-growing Eurasian fern (Polypodium vulgare) characterized by creeping stems that form dense mats.