Isoetes tegetiformans

Common Names:
mat-forming quillwort, Merlin's grass
Growth Habit:
CPC Number:
Profile Contributors:
Fully Sponsored

Reference Links

ITIS - Tropicos - USDA Plants - Fish & WildLife

Participating Institutions

The following Participating Institutions are custodians for this species in the CPC National Collection:
North Carolina Botanical Garden

The conservation of Isoetes tegetiformans is fully sponsored.


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.

Distribution & Occurrence


Conservation, Ecology & Research