Although it cannot be classed among the rare ferns, it is absent from many promising localities, and is associated in my mind with especially successful expeditions.
26. RUE SPLEENWORT. WALL RUE
Asplenium Ruta-muraria
A small rock fern, growing on limestone, Vermont to Michigan and southward. Four to seven inches long, with green, slender, tufted stalks.
Fronds.—Triangular-ovate, smooth, evergreen, twice or thrice-pinnate below; pinnæ cut into stalked pinnules; fruit-dots confluent at maturity, covering nearly the whole lower surface of pinnules; indusium delicate.
My first acquaintance with the little Rue Spleenwort in its own home dates back to the memorable day when we discovered the new station for the Hart's Tongue.
PLATE XVII
RUE SPLEENWORT