Narrow-leaved Sword-fern, Imbricate Sword Fern
Polystichum imbricans ssp. imbricans
Synonym: Polystichum munitum var. imbricans
The photo above shows a cluster of the fronds
of imbricate sword fern arising from a rock face along forest road #2360 just
north of its intersection with road #071 on the southwestern slopes of Mt. Adams.............October
14, 2005. Note the numerous persistent, dried fronds at the base of the plant.
The photo above shows several different leaflets of imbricate
sword fern. The lower leaflet shows a dorsal view, while the
two upper leaflets show ventral views with their spore cases. Note the spreading
to spreading-ascending spines along the margin of the lowermost leaflet. Photographed
in talus just downslope of the Mt. Adams Viewpoint along Rd #23, about one-half
mile south of the intersection with Rd #8810...........September 25, 2005.
The photo above shows a close-up of one leathery
leaflet of imbricate sword fern with its closely spaced spore capsules. Note
the central, light colored indusium in each spore capsule. Photographed in talus
just downslope of the Mt. Adams Viewpoint along Rd #23, about one-half mile
south of the intersection with Rd #8810...........September 25, 2005.
The upper half of a frond of imbricate sword
fern as seen in talus just downslope of the Mt. Adams Viewpoint along Rd #23,
about one-half mile south of the intersection with Rd #8810...........September
25, 2005. Note the large tooth at the base of each leaflet that is not cut into
the leaflet. The leaflets at the base of the frond are either the longest on
the frond, or about the same size as those at mid frond.
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The photo above show close-ups of imbricate sword fern as seen on a large lava outcrop on the uphill side of the Round the Mt. Trail #9 to the west of Shorthorn Creek in the Mt. Adams Wilderness..........September 5, 2006. Lacelip fern (Cheilanthes gracillima), Cascade rockbrake (Cryptogramma cascadensis) and brittle fern (Cystopteris ffragilis) are also found at this location. Click each photo to see an enlarged version.
Imbricate sword fern spotted at about 6900' on the terminal moraine for the Adams Glacier above the headwaters of the Lewis River, Mt. Adams Wilderness......July 19, 2018.
Paul Slichter