Description: This native perennial fern has deciduous compound leaves up to 3' tall and 1' across; the ascending to widely spreading leaves are arranged together in loose tufts. The petioles are shorter than the leaf blades; they are terete and variably colored – usually green, tan, or brown. Each petiole usually has a few light brown scales and abundant white hairs, particularly near the base. Each leaf blade is pinnate-pinnatifid in structure and ovate to ovate-lanceolate in outline; it has about 15-25 pairs of leaflets and is widest toward toward the middle or lower-middle. Each pinnatifid leaflet is up to 6" long and linear-oblong in outline; it has about 8-22 pairs of lobes, which are spaced closely together. Each leaflet-lobe is short-oblong in shape and smooth or slightly crenate along its margins. The upper surface of each leaf blade is hairless to mostly hairless and dull olive green to bright medium green. The rachis (or central stalk) of the leaf blade is covered with fine silvery hairs, especially on the underside. The lower surface of each leaf blade is pale to medium green and mostly hairless. Each leaflet-lobe has pinnate venation; the lateral veins are not forked.
For fertile leaves, there are 2 rows of
elongated sori (spore-bearing structures) that are parallel to the lateral
veins on the underside of each leaflet-lobe. These sori are partially covered
by elongated indusia (protective membranes) that become silvery in appearance.
The sori and indusia are straight to slightly curved. The spores are released
from the sori during the summer or fall; they are distributed by the wind. The
root system consists of stout lateral rhizomes and abundant fibrous roots.
Dense vegetative colonies are often formed from the rhizomes.
Cultivation: The preference is light to medium
shade, moist to mesic conditions, and a light loamy soil with decaying organic
matter (slightly acid to neutral pH). Fairly high humidity and some protection
from the wind are desirable. 
Range &
Habitat: Silvery Glade Fern is distributed throughout Illinois (see
Distribution
Map); it is occasional in most areas, but colonies of plants are often
widely scattered from each other. Habitats include moist to mesic deciduous
woodlands, wooded valleys, and slopes of wooded ravines above streams. This
terrestrial fern is often found along wooded slopes that were formed from
either glacial till or underlying bedrock.
Faunal Associations: Information about floral-faunal
relationships for this fern are unavailable.
Photographic Location: The lower-middle slope of a
wooded ravine in Vermillion County, Illinois.
Comments: This is a rather stout and handsome fern.
The Silvery Glade Fern has an unstable taxonomic history. Older scientific
names of this fern include Asplenium acrostichoides, Athyrium
acrostichoides, Athyrium thelypterioides, and Diplazium
acrostichoides. Because of an early assignment to the Asplenium
genus, this fern is sometimes called 'Silvery Spleenwort,' even though it bears
little resemblance to the ferns in this genus. In many ways, the Silvery Glade
Fern is similar in appearance to Athyrium felix-femina (Lady Fern).
However, the latter fern lacks hairy petioles and rachises, and the shape of
its elongated sori and indusia are usually more curved (sickle-shaped). Unlike
the Silvery Glade Fern, which has undivided lateral veins on the undersides of
its leaflet lobes, the similar Osmunda claytoniana (Interrupted Fern)
and Osmunda cinnamomea (Cinnamon Fern) have forked lateral veins. These
latter two ferns also differ by producing unexpanded leaves or leaf-segments
that are heavily covered with brown sori.