Black-spored Quillwort

Isoetes melanospora

Description

Isoetes melanospora (black-spored quillwort) is an aquatic plant with chive-like leaves, 0.8-2.8 in (2-7 cm) long, that spiral upward from a swollen base, called a corm. The plant puts down many fleshy, branched roots that anchor it to the thin soil. Quill-worts, which are related to ferns, do not reproduce by seed but by spores. Reproductive spores develop in nodes formed at the base of the leaves.

The family of quillworts has only a single genus, containing about 70 species. Many have a similar appearance and are best differentiated by spore characteristics. Black-spored quillwort, also called Merlin's grass, occasionally hybridizes with Isoetes piedmontana, a more common granite outcrop quill-wort.

Habitat

Black-spored quillwort grows in rock-rimmed seasonal pools atop granite outcrops in domed or gently rolling areas known locally as "flatrocks." Most pools are only about 3 ft (1 m) across, with a thin bottom deposit of sand or silt that is low in organic matter. These pools fill up after heavy rains, but evaporate quickly, and are usually completely dry by mid-summer. Black-spored quillwort grows quickly when water is available, frequently in association with amphianthus species, one of which— little amphianthus (Amphianthus pusillus )—is federally listed as Endangered.

Distribution

Black-spored quillwort was discovered on Stone Mountain in DeKalb County, Georgia, in 1877. It has subsequently been found at 11 other sites in central Georgia and one site in South Carolina. As of 1993, the species was thought to be extant at only eight locations, all in Georgia (in Butts, DeKalb, Gwinnett, Heard and Rockdale counties). The largest remaining population occurs at Davidson-Arabia Mountain Park in DeKalb County.

It is extinct at five historical sites in DeKalb and Newton counties. Due to hybridization, it is considered extinct or essentially so at the sole reported site in South Carolina (in Lancaster County) and at two additional sites in Georgia (Butts and DeKalb counties). Only one site supports more than three inhabited pools. The typical site has one or two pools totaling only a few square meters.

By 1993, two of the eight extant locations (both in DeKalb County) were publicly owned. The type locality, Stone Mountain, lies within the state-owned Georgia Stone Mountain Park.

Threats

Black-spored quillwort is threatened by continuing loss of its habitat. Georgia's "flatrocks" are being quarried at a tremendous pace, making the state the world's largest producer of granite building stone. Over 40% of historic quillwort populations have already been lost to quarrying.

Conservation and Recovery

Georgia law prohibits collection of these plants without a permit and regulates interstate transport, but does not protect the plant against habitat destruction. Recovery strategies include the preservation of some "flatrocks" habitat, which requires bringing suitable outcrops into public ownership or encouraging purchase by private conservation groups. The 1993 Fish and Wildlife Service Recovery Plan for Three Granite Outcrop Plant Species (including the black-spored quillwort) notes that the initial recovery objective for the species is down-listing to Threatened status; delisting (removal from the list altogether) potential could not be determined at the time of the plan's release.

Reclassification to Threatened status will be considered if 10 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. 1981. "Intersectional Hybrids inIsoetes." American Fern Journal 70:1-4.

Rayner, D. A. 1986. "Granite Flatrock Outcrops inSouth Carolina." Bulletin of South Carolina Academy of Science 43:106-107.

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

Wharton, C. H. 1978. The Natural Environments of Georgia. Georgia Department of Natural Resources, Atlanta.