Description: This native perennial fern produces
small clumps of simple-pinnate leaves. Individual leaves are
¾–1½' long and 1-2" across; the semi-evergreen fertile
leaves are longer and more erect than the evergreen sterile leaves. Each
compound leaf has 15-40 pairs of leaflets along its rachis (or central stalk);
these leaflets are usually arranged alternately along the rachis, rather than
in opposite pairs. Both the rachis and petiole of mature leaves are terete and
dark purplish brown; usually they are glabrous, but sometimes sparse white
hairs are present. For very young leaves emerging from the ground, the rachis
and petiole can be light green. Individual petioles (about 1-4" long) are much
shorter than the leaf blades. The medium to dark green leaflets are
deltoid-oblong in shape, crenate or serrate along their margins, and glabrous;
young leaflets often have a lustrous quality. The base of each leaflet has an
ear (auricle) on the upper side that overlaps the rachis. Each leaflet has
pinnate venation with a central vein and several lateral veins; the lateral
veins are forked. On fertile leaves, mature leaflets develop two rows of
elongated sori (spore-bearing structures) on their undersides. Attached to one
side of each sorus, there is an elongated
indusium (protective membrane) that eventually withers
away. The spores are released to the wind during the summer or early fall. The
root system consists of a short rhizome with fibrous roots; relative to ground
surface, the position of this rhizome is often vertical or diagonal in its
orientation.
Cultivation: This fern
prefers partial sun or dappled sunlight, moist to slightly dry conditions, and
soil that is loamy or rocky. Unlike many other Asplenium spp.
(spleenworts), which are restricted to very rocky habitats, Ebony Spleenwort
adapts to terrestrial conditions. Thus, it is more likely to thrive in
gardens.
Range & Habitat: Ebony
Spleenwort is occasional to locally common in the southern half of Illinois,
while in the northern half of the state it is uncommon or absent (see
Distribution
Map). However, this fern has been spreading into new locations northward,
even reaching the upper Great Lakes region. Habitats include thin upland
woodlands, sandy woodlands, rocky wooded slopes, rocky cliffs and ledges (if
not too sunny and dry), small meadows in upland wooded areas, rocky glades, and
rocky banks along roads. In the rocky habitats, some seepage of groundwater may
occur. Ebony Spleenwort is occasionally found in habitats with a history of
disturbance (e.g., removal of some trees or brush in wooded
areas).
Faunal Associations:
Information about floral-faunal relationships is unavailable.
Photographic Location: Edge of a small meadow in an
upland woodland in Vermillion County, Illinois. The use of a flash on the
camera has caused the color of the leaves to wash out.
Comments: This is the largest and most adaptable
spleenwort in Illinois; the attractive leaves have a delicate appearance. It
superficially resembles a small-sized Polystichum acrostichoides
(Christmas Fern), but the rachis and petiole of the latter fern are
light-colored and very scaly. Among the various Asplenium spp.
(spleenworts) in Illinois, the most similar species is Asplenium
resiliens (Black Spleenwort), which has been called "Little Ebony
Spleenwort." Black Spleenwort has smaller leaves (about 4-9" long &
½–1" across) than Ebony Spleenwort, and the ears of its leaflets
don't overlap or hide the rachis to the same extent as the eared leaflets of
the latter fern. Other similar spleenworts in Illinois have leaflets that lack
eared basal lobes and their leaflets are often as wide as long. Furthermore,
the mature petioles and rachises of such spleenworts are light-colored (green
or yellowish tan) in whole or part. Ebony Spleenwort occasionally hybridizes
with other spleenworts when they occur together in the same
area.