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

George Lawson (botanist)

George Lawson was a Scottish-Canadian botanist who is considered the "father of Canadian botany".Born in Scotland, in 1858, he was appointed the Professor of Chemistry and Natural History at Queen's University...

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This species is an allotetraploid of hybrid origin (see Cystopteris hybrid complex

Cystopteris hybrid complex

-North American Cystopteris Hybrids:The diploid parent species within the genus include:*C. bulbifera*C. "hemifragilis" *C. protrusa*C. reevesianaThe hybrid species include:...

. The parent diploid species are Cystopteris protrusa

Cystopteris protrusa

Cystopteris protrusa is a common fern of eastern North America. Throughout much of its range, it is the most common Cystopteris. It is commonly known as the lowland brittle fern or lowland fragile fern...

and the hypothesized Cystopteris hemifragilis, believed to be an extinct species.

Mackay's fragile fern grows on rock or in scree, generally in sheltered spots, in the northeastern United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

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