Cystopteris Bernhardi (Woodsiaceae) Earlier placement: Athyriaceae, Cystopteridaceae, Dryopteridaceae

Bladder fern

Etymology Greek: kystos, bladder + pteron, wing, which describes the pinnae. Note that the ancient Greeks used pteris to describe all ferns. The indusium looks like an inflated bladder.
Description Rhizome: short- to long-creeping, scaly.
Frond: deciduous, the stipe bases persistent, storing starch, monomorphic.
Stipe: grooved, hairy or glabrous, vascular bundles: 2, round or oblong.
Blade: 1-3 pinnate-pinnatifid, ovate-lanceolate to deltate, membranaceous to herbaceous, absent or of uniseriate, multicellular hairs in pinnae axils or of unicellular, gland-tipped hairs below.
Pinnae: anadromous, costae grooves above continuous from rachis to costae, segments serrate-dentate, veins free, simple or forked, ending at the margin.
Sori: round, in 1 row between midrib and margin, indusium: young: hood-shaped, often falling at maturity, beneath sorus on midrib side, sporangia: brown.
Cystopteris fragilis. Sori and venation. C. fragilis is cosmopolitan, this photo taken at Parque Nacional Amboro, Bolivia, the species occuring at 1900-2550 m.  Photo by Michael Sundue, New York Botanic Garden

The sporangia of Cystopteris tenuis are fully exposed at maturity.  Photo: Robert W. Freckmann, with permission.
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