Asplenium ruta-muraria wallrue

Wall rue is a rare fern, very delicate, feathery, of light green with branched clusters of small, long-stalked pinnae with stalked and palm-shaped pinnules, growing on basic rocks (limestone).

The species name 'ruta-muraria' was given to this fern by Linneaus from the Greek, meaning 'rue of the wall', as the fern prefers to grow on limestone rock and its leaves are reminiscent to those of meadow rues.

Could be confused with Pellaea atropurpurea.

Habitat & Range

Grows on sheltered boulders and cliffs, in smallest seams or crevices of limestone and other calcerous rock outcroppings, never in open sun.

Range is from Vermont to Michigan, south to Alabama and Missouri.

Wetland code: Not classified

Characteristics

Blade olive or bluish green, smooth, somewhat leathery and feathery, grows to 7 in long.

Pinnae widely spaced, stalked, with 2-7 widely spaced pinnules, alternate.

Pinnules amostly fan-shaped on distinct stalks, edges fringed, indented or toothed.

Rachis green, smooth, dull, grooved in front and delicate with very sparse, tiny hairs.

Stipe usually longer than blade ( up to 3 1/2 in long), very slender, grooved in front, smooth and green, except at the

very base where it is dark brown and somewhat scaly.

Rhizome short, ascending or creeping (ascending more common) with many old, dead stipes attached. Covered with many tiny, pointed, dark brown scales hidden among roots.

Sori short and narrow, often massed together and cover the whole underside of the pinnule completely. Indusium whitish with hairy edges, delicately membranous.