Mat-forming Quillwort

Isoetes tegetiformans

Description

Isoetes tegetiformans (mat-forming quillwort) is a low-growing, aquatic plant with short, chive-like leaves, spiraling upward from a bulb-like base, called a corm. Individual plants are connected by a fleshy underground rhizome. The stems rise to form a dense mat on the surface of the water, a habit that distinguishes this quillwort from other members of its genus, such as the Endangered black-spored quillwort (Isoetes melanospora ).

Quillworts produce spores rather than seeds and are closely related to club mosses and spike mosses. The swollen base of the plant contains both male and female reproductive spores that disperse to produce new plants. The size and shape of the spores, which can only be determined under the microscope, is used to differentiate species. Mat-forming quillwort appears to depend as much on vegetative reproduction from its rhizome as on reproduction by spores.

Habitat

The species is found in the temporary and seasonal pools that dot the gently rolling granite "flatrocks" landscape of the Southeastern Piedmont. Granite outcrop pools typically have bottoms of thin sandy or silty soil containing little organic matter. Pools retain water for several weeks after heavy rains, but usually dry up completely in summer.

Distribution

Mat-forming quillwort is endemic to the flatrocks of central Georgia in the region northeast of Macon and west of Augusta. It was first described in 1978 from material collected at Heggie's Rock Preserve in Columbia County, Georgia.

As of 1993, the species was restricted to four Georgia counties, Columbia, Greene, Hancock and Putnam. Three of the seven extant sites are in Columba County; prior to quarrying activities, it occurred at three additional outcrops in that county. The largest population occurs in Hancock County.

Following its discovery, the U.S. Fish and Wild-life Service (FWS) conducted an extensive search of more than 120 granite outcrop sites in Georgia, locating only ten additional populations of mat-forming quillwort. Since that time, the population sites have dwindled. Most sites consist of one or two pools that support quillwort colonies. Although vegetation at these sites appears dense, pools actually contain few genetically distinct individuals since the plant spreads through its rhizome.

All sites for the mat-forming quillwort were in private ownership as of 1993. The type locality, Heggies Rock, is owned by the Nature Conservancy (TNC) and occupies a single, larger-than-average vernal pool. The population is healthy and shows recovery from past vehicular traffic. The two largest populations (in Greene and Hancock counties) are owned by the Georgia-Pacific Corporation.

Threats

Georgia is the world's largest granite producer. Quarrying of granite outcrops has gone on for two hundred years and will certainly continue, steadily constricting the quillwort's habitat. Granite out-crops of the "flatrocks" are also popular as recreational sites, and many pools with quillwort populations have been damaged by hikers or by off-road vehicles.

Conservation and Recovery

TNC owns and manages Heggie's Rock Preserve in Columbia County, which protects one pool with quillwort populations.

The 1993 FWS Recovery Plan for Three Granite Outcrop Plant Species (including the mat-forming quillwort) notes that the initial recovery objective for the species is downlisting to Threatened status; whether de-listing (removal from the list altogether) is possible could not be determined at the time of the Recovery Plan's release.

Reclassification to Threatened status will be considered if ten viable and geographically distinct populations (separate outcrops), each with at least two occupied pools, are protected from any foreseeable threats. To achieve this goal, the plan recommends a variety of actions, including the protection of populations and habitat; the preservation of genetic stock from acutely threatened populations; and the monitoring of populations to determine trends and developing threats. The plan also calls for the reestablishment of populations and the augmentation of extant populations at protected locations, if deemed necessary. Management techniques should also be used to maintain and/or enhance populations, and public education programs should be established to spread the word about the value and fragility of the species and its habitat.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
http://southeast.fws.gov/

References

Boom, B. M. 1982. "A Synopsis of Isoetes in the Southeastern United States." Castanea 47:38-59.

Matthews, J. F., and W. H. Murdy. 1969. "A StudyIsoetes Common to the Granite Outcrops of the Southeastern Piedmont, United States." Botanical Gazette 130:53-61.

Rury, P. M. 1978. "A New and Unique Mat-Forming Merlin's Grass (Isoetes ) from Georgia." American Fern Journal 68:99-108.

Rury, P. M. 1985. "New Locations for Isoetes tegetiformans in Georgia." American Fern Journal 75:102-104.

U.S. Fish and Wildlife Service. 1993."Recovery Plan for Three Granite Outcrop Plants Species." U.S. Fish and Wildlife Service, Jackson, Mississippi.