CPC Plant Profile: Merlin's-grass
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Plant Profile

Merlin's-grass (Isoetes tegetiformans)

This picture shows the black-spored quillwort. Photo Credit: Frank R. Thibodeau
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Isoetaceae
  • State: GA
  • Nature Serve ID: 139444
  • Date Inducted in National Collection: 05/28/1986

Mat-forming quillwort is a small, rooted aquatic emergent found in very shallow pools on granitic flat rock. Individual plants have a slender, centrally furrowed, prostrate azil ca. 1 mm thick. The population structure is dense and mat forming, with the adventitious buds cauline perennial fern ally. Considered North Americas most distinctive quillwort (Rury 1978), Isoetes tegetiformans has steadily declined in numbers since its discovery in 1978. This diminutive fern ally is adapted to a very specialized habitat and environmental conditions. It is found only on granitic outcrops in Georgia, where quarrying has destroyed many populations and continues to limit potential sites. The nutrient-poor conditions to which Isoetes tegetiformans is adapted have been altered by conversion to pasture. Eutrophication caused by cattle waste favors the growth of other aquatics that thrive in nutrient-rich conditions, and causes algal blooms that deplete the water of oxygen. Because reproduction is predominantly asexual in Isoetes tegetiformans, its colonies lack genetic diversity, and therefore have limited ability to adapt to these environmental changes. (USFWS 1993) For this reason, preserving habitat that meets the specialized requirements of this unique species should continue to be a top priority.

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Nature Serve Biotics
  • 05/02/2017

Endemic to granite outcrops in Georgia. Despite intensive surveys only 7 small populations are known to be surviving, and these are vulnerable to habitat destruction, especially from quarrying. 3 populations have been lost since the species was first discovered in 1976.

  • 01/01/2010

Destruction of habitat from quarrying activities (has destroyed 9% of total population) Heavy recreational use (trail bicycles, ORV traffic, littering, vandalism, fire building) Eutrophication resulting from conversion of habitat to pasture (cattle w

  • 01/01/2010

7 populations (USFWS 1993)

  • 01/01/2010

Van De Genachte (1996) Studied the conservation genetics of the granite outcrop quillworts Isoetes melanospora and Isoetes tegetiformans for a Masters Thesis at University of Georgia. A summary of this work can be seen in Musselman (2001).

  • 01/01/2010

Population at Heggies Rock Preserve is owned by TNC, and has been monitored between 1985 and 1989. Some recovery from past vehicular traffic has been reported at this site (USFWS 1993). Plants exist in cultivation at the North Carolina Botanical Garden and at the Atlanta Botanic Garden (USFWS 1993)

  • 01/01/2010

Protect current populations through land acquisition or by the negotiation of management agreements with private owners Continue population monitoring Assess the potential for reintroduction or habitat restoration efforts

  • 01/01/2010

Establish protocol for germination, and for maintenance of plants in cultivation.


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Taxon Isoetes tegetiformans
Authority Rury
Family Isoetaceae
CPC Number 2348
ITIS 17141
Common Names mat-forming quillwort | Merlin's grass
Associated Scientific Names Isoetes tegetiformans
Distribution Georgia (Columbia, Greene, Hancock, and Putnam Counties) (USFWS 1993)
State Rank
State State Rank
Georgia S1

Shallow vernal pools on granite outcrops (USFWS 1993)

Ecological Relationships

Adapted to a specialized microhabitat characterized by (1) a substrate of acidic, nutrient-poor mineral soil, and (2) an environment fluctuating between hydric and xeric several times between May and October (USFWS 1993). A unique feature of the reproductive biology of this species is that it exhibits clonal reproduction in addition to sexual reproduction (by spores). This means that individual pools may contain few genetic individuals (Bridges 1986)

Common Name Name in Text Association Type Source InteractionID
Lead Institution State Reintroduction Type Year of First Outplanting

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