wall rue
noun
1.
a small, delicate fern,
Asplenium rutamuraria,
having fan-shaped leaflets and growing on walls and cliffs.
Origin
1540-50
British Dictionary definitions for
wall rue
wall rue
noun
1.
a delicate fern,
Asplenium ruta-muraria,
that grows in rocky crevices and walls in North America and Eurasia