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Cystopteris fragilis kz1.jpg
Cystopteris fragilis
Scientific classification e
Kingdom: Plantae
Division: Pteridophyta
Class: Polypodiopsida/Pteridopsida
Order: Polypodiales
(unranked): Eupolypods II
Family: Cystopteridaceae
Genus: Cystopteris

10-20: see text

Cystopteris is a genus of ferns in the family Cystopteridaceae.[1] These are known generally as bladderferns or fragile ferns. They are found in temperate areas worldwide. This is a very diverse genus and within a species individuals can look quite different, especially in harsh environments where they experience stress and remain small and stunted. Also, they hybridize easily with each other. Identifying an individual can be challenging. In general these are rhizomatous perennials which may grow in rocky areas or in soil. Their leaves are multiply pinnate, in that each leaflet is divided into smaller parts. The sori are usually rounded and are covered in an inflated bladder-like indusium.


Species include:[2]


Cystopteris widely hybridizes internally.

North American Cystopteris hybrids[edit]

The diploid parent species within the genus include:

The hybrid species include:

  • C. fragilis (C. "hemifragilis" × C. reevesiana; allotetraploid)
  • C. laurentiana (C. bulbifera × C. fragilis; allohexaploid)
  • C. tennesseensis (C. bulbifera × C. protrusa; allotetraploid)
  • C. tenuis (C. "hemifragilis" × C. protrusa; allotetraploid)
  • C. utahensis (C. reevesiana × C. bulbifera; allotetraploid)

Non-species hybrids include:

  • Cystopteris × illinoensis (C. bulbifera × C. tenuis; allotriploid)
  • Cystopteris × wagneri (C. tennesseensis × C. tenuis; allo-allotetraploid)
  • Cystopteris fragilis × Cystopteris tenuis (allo-allotetraploid)
  • Cystopteris protrusa × Cystopteris tennesseensis (allotriploid)


  1. ^ Maarten J. M. Christenhusz, Xian-Chun Zhang & Harald Schneider (2011). "A linear sequence of extant families and genera of lycophytes and ferns" (PDF). Phytotaxa. 19: 7–54. 
  2. ^ Cystopteris Bernh. Missouri Botanical Garden. 29 Feb 2012