Description: This native perennial fern consists of a clump of several compound leaves up to 6' tall. The petioles of these leaves are erect or ascending, while their branches are ascending to spreading. Both the petioles and branches of the leaves are hairless and variably colored – light green, tan, brown, or reddish brown – depending on maturity and exposure to light. The structure of each compound leaf is bipinnate, consisting of 6 or more pairs of pinnate leaflets. Each pinnate leaflet usually consists of 10 or more subleaflets that are organized into two alternate ranks along the central stalk of the leaflet; however, small terminal leaflets may have fewer subleaflets.
The individual subleaflets are about 2"
long and 1/3 as much across; they are light to medium green, oblong, hairless,
and very finely serrated along their margins. The subleaflets may spread
outward from the central stalk, or they may spread upward at about a 30º
angle. The base of each subleaflet is rounded, but asymmetrical, where there is
a short basal stalk (a petiolule). The upper branches of some compound leaves
have fertile leaflets. Each fertile leaflet is an oblongoid cluster of small
subleaflets that are bead-like in shape. Each of these fertile subleaflets
contains numerous sporangia (spore-bearing structures); these subleaflets soon
become brown and eventually split open to release their spores. The root system
consists of a stout vertical rootstalk that produces the compound leaves; this
rootstalk is surrounded by a dense mass of wiry fibrous roots. Older plants can
form small tussocks above the dense mass of their root systems. Colonies of
plants are occasionally formed from vegetative offsets at favorable
sites.
Cultivation: Full sun to
light shade, wet to mesic conditions, and a sandy acidic soil with organic
matter are preferred. This fern also tolerates soil that is rocky (if not too
alkaline) or silty. This fern also tolerates temporary flooding. The foliage
may become pale yellowish green in full sun, particularly during hot dry
weather.
Range & Habitat: Royal
Fern occurs in scattered locations across Illinois (see Distribution Map). It
is occasional in sandy areas of northern Illinois, sandy areas of central
Illinois, and rocky areas of southern Illinois where sandstone occurs;
elsewhere in the state, it is uncommon or absent. Royal Fern also occurs in
tropical America, Africa, and Europe. In Illinois, habitats include sandy
savannas, sandy thickets, areas along paths in sandy woodlands, moist sand
prairies, swamps, sandy or gravelly seeps, remnant bogs, borders of streams and
ponds (particularly in sandy areas), rocky bluffs, and sandstone cliffs. This
fern is found in high quality natural habitats.
Faunal Associations: This large fern occasionally
forms sizable colonies that provide cover for wildlife. The foliage may be
browsed by deer to a limited extent.
Photographic Location: Along a path in a sandy
savanna at Hooper Branch Savanna Nature Preserve in Kankakee County,
Illinois.
Comments: From a distance,
this fern appears almost shrub-like. It is quite large and imposing, and there
is really nothing else that resembles it. Royal Fern tolerates more light than
most other ferns, and it is even found in moist sand prairies in northern
Illinois, where it occurs with Pteridium aquilinum (Bracken Fern) and
Onoclea sensibilis (Sensitive Fern). Other members of the Royal Fern
family in Illinois include Osmunda claytoniana (Interrupted Fern) and
Osmunda cinnamomea (Cinnamon Fern). These very attractive ferns have
pinnate-pinnatifid leaves with a more lacy appearance than the bipinnate leaves
of Royal Fern, although the reproductive structures of their fertile leaves are
similar.