''Cystopteris protrusa'' is a common fern of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, commonly known as the lowland bladderfern, lowland brittle fern or lowland fragile fern. The plant is native to eastern Canada, and the

Midwestern The Midwestern United States (also referred to as the Midwest, the Heartland or the American Midwest) is one of the four census regions defined by the United States Census Bureau. It occupies the northern central part of the United States. It ...

and

Eastern United States The Eastern United States, often abbreviated as simply the East, is a macroregion of the United States located to the east of the Mississippi River. It includes 17–26 states and Washington, D.C., the national capital. As of 2011, the Eastern ...

. Throughout much of its range it is the most common ''

Cystopteris ''Cystopteris'' is a genus of ferns in the family Cystopteridaceae. These are known generally as bladderferns or fragile ferns. They grow in temperate areas worldwide. This is a very diverse genus and within a species individuals can look quite ...

'' fern species.

Description

Unlike most species of the genus ''

'', this fern is exclusively terrestrial, often forming large, dense colonies. It is also largely a spring ephemeral. Some fronds may remain by late summer, but most have disappeared. The specific name, protrusa, refers to the fact that the rhizome protrudes a short distance beyond the current year's fronds to form the following year's leaf buds. This protrusion is a positive diagnostic in the field. Sori are round and covered in a bladder-like

indusium A sorus (: sori) is a cluster of sporangia (structures producing and containing spores) in ferns and fungi. A coenosorus (: coenosori) is a compound sorus composed of multiple, fused sori. Etymology This Neo-Latin word is from Ancient Greek � ...

Taxonomy

''Cystopteris protrusa'' was originally considered only a variety of '' Cystopteris fragilis''. However, it is now known that this is a diploid species, while ''C. fragilis'' (ss) is a polyploid species of hybrid origin. ''C. protrusa'' is a parent of the hybrid species '' Cystopteris tennesseensis'' and ''

Cystopteris tenuis ''Cystopteris tenuis'' is sometimes known as Mackay's bladder fern or Mackay's fragile fern. It was long considered to be a part of the superspecies for fragile ferns, as ''Cystopteris fragilis'' ( L.) Bernh. var. ''mackayi'' Lawson. left, ' ...

''.

References

External links

USDA Plants Profile for ''Cystopteris protrusa'' (lowland bladderfern)
protrusa Ferns of Canada Ferns of the United States Plants described in 1935 {{Polypodiales-stub

Description

Taxonomy

See also

References

External links