Foothills to subalpine. Rocks. Summer.
Above: Cross Mountain Trail, August 5, 2019.
Left: Lizard Head Trail, June 19, 2004.

Cystopteris fragilis occurs in many states and is the most common fern at high elevations in the San Juan Mountains and nearby mountains of the Four Corners area.  It tucks itself into rock crevices, often fading with summer dryness and reappearing with fall coolness and moisture. At the far left of the top photograph are fronds of Cryptogramma acrostichoides. 

Linnaeus named this species Polypodium fragile in 1753 from specimens collected in northern Europe.  Johann Bernhardi renamed it Cystopteris fragilis in 1806.

Foothills to subalpine. Rocks. Summer.
Lizard Head Trail, August 4, 2010 and East Fork Trail, September 7, 2011.

Grape-like clusters on the underside of the Cystopteris fragilis leaflets are the sori which contain sporangia which in turn contain spores, the reproductive cells of ferns.

Cystopteris reevesiana (Reeves' Brittlefern)
Cystopteridaceae (Wood Fern Family). Synonyms: Woodsiaceae, Athyriaceae, Polypodiaceae, Dryopteridaceae.

Foothills to subalpine. Rocks. Summer.
Lizard Head Trail, June 19, 2004.

Cystopteris reevesiana and Cystopteris fragilis are very similar, both in their appearance and in their habitat.  Weber and the Flora of North America disagree on a number of prominent characteristics that separate the two species but they do agree that C. reevesiana leaflets are more widely spaced and deeply cut, as is shown in the photographs on this page.  They also agree that C. reevesiana is found almost exclusively in the Four Corners states.

There is agreement that it is common to find the two plants growing very close to one another in rocky montane areas of the Four Corners states.

In 1981 David Lellinger named this species for Tim Reeves, Fern expert and Professor at San Juan Community College, Farmington, New Mexico. (Click for more biographical information about Tim Reeves.)

Cystopteris reevesiana (Reeves' Brittlefern)
Cystopteridaceae (Wood Fern Family). Synonyms: Woodsiaceae, Athyriaceae, Polypodiaceae, Dryopteridaceae.

Foothills to subalpine. Rocks. Summer.
Lizard Head Trail, June 19, 2004.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Cystopteris fragilis

Range map for Cystopteris reevesiana