wall rue

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A small, delicate fern (Asplenium ruta-muraria) that grows on rocks or in rocky crevices.

from The Century Dictionary.

• noun A small delicate fern, Asplenium Ruta-muraria, growing on walls and cliffs. Also called rue-fern, wall-pie, tentwort, and wall-rue spleenwort.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun small delicate spleenwort found on a steep slope (as a wall or cliff) of Eurasia and North America