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Isoetes georgiana N. Luebke
Georgia Quillwort
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G2G3
State Rank: S2?
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): No
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: Highest Conservation Concern
Element Occurrences (EOs) in Georgia: 13
Habitat Summary for element in Georgia: In floodplain woods on seasonally wet or inundated margins of braided streams
Perennial herb rising from a rootstock and forming clumps in flowing water and on exposed banks of woodlands streams. The rootstock (corm) is nearly round, with two lobes. Leaves arise from directly from the corm and are up to 16 inches (40 cm) long, olive green to blackish-green, fading to white at the base, flexible, with an expanded base, tapering tip, 4 cross-walls, and single midvein. Old, dark brown to black leaf bases persist on the top of the corm. Spores are produced in the sporangium, a brown-streaked chamber, about 0.25 inch (5 - 9 mm) long, in the leaf base, with a transparent membrane (velum) covering 55 - 60% of the chamber opening. Dozens of white female spores (megaspores), 0.6 mm across (relatively large for Isoetes) and covered with broad, blunt-crested, and interconnecting ridges, may be seen with 10 - 20x magnification. Light brown, dust-sized male spores (microspores) are produced on separate leaves but are indistinguishable without much higher magnification.
Quillworts are distinguished from flowering, wetland plants by their spongy leaves with conspicuous cross-walls and by the presence of sporangia in the dilated base of the leaves.
Southern quillwort (Isoetes flaccida) occurs in habitats similar to Georgia quillwort’s, and also has long, flexible leaves; however, its velum completely covers the spore chamber, which is colorless, not streaked with brown; its megaspores are much smaller and have a bumpy surface. For more information, see: https://www.georgiabiodiversity.a2hosted.com/portal/profile?group=plants&es_id=19963
Boom’s quillwort (I. boomii) is similar but with shorter velum coverage and a more congested, intricate megaspore ornamentation pattern. For more information, see: https://www.georgiabiodiversity.a2hosted.com/portal/profile?group=plants&es_id=17134).
Engelmann’s quillwort (I. engelmannii) and Appalachian quillwort (I. appalachiana) have smaller megaspores with reticulate (honey-comb) ornamentation patterns and smaller velum coverage (less than 30%) over their sporangia. For more information, see: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250076852 http://explorer.natureserve.org/servlet/NatureServe?searchName=Isoetes+appalachiana
Winter quillwort (I. hyemalis) also has smaller megaspores with a coarse, low-spiny ornamentation pattern and smaller velum coverage (less than 25%) over the sporangia. For more information, see: https://www.georgiabiodiversity.a2hosted.com/portal/profile?group=plants&es_id=17363
Twelve quillwort species are state-listed or considered of Special Concern in Georgia. Information about each of these species may be found at these links:
Boom's Quillwort (Isoetes boomii) https://www.georgiabiodiversity.org/portal/profile?group=plants&es_id=17134
Appalachian Quillwort (Isoetes appalachiana) http://explorer.natureserve.org/servlet/NatureServe?searchName=Isoetes+appalachiana
Glade Quillwort (Isoetes butleri) http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250076861
Florida Quillwort (Isoetes flaccida) https://www.georgiabiodiversity.org/portal/profile?group=plants&es_id=19963
Georgia Quillwort (Isoetes georgiana) https://www.georgiabiodiversity.org/portal/profile?group=plants&es_id=16950
Winter Quillwort (Isoetes hyemalis) https://www.georgiabiodiversity.org/portal/profile?group=plants&es_id=17363
Rush Quillwort (Isoetes junciformis) https://www.georgiabiodiversity.org/portal/profile?group=plants&es_id=18998
Black-footed Quillwort (Isoetes melanopoda) http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250076862
Black-spored Quillwort (Isoetes melanospora) https://www.georgiabiodiversity.org/portal/profile?group=plants&es_id=22510
Broxton Rocks Quillwort (Isoetes "snowii," undescribed) https://bioone.org/journals/castanea/volume-83/issue-2/17-122/Interesting-Provocative-and-Enigmatic--Morphological-Observations-on-Southeastern-Quillworts/10.2179/17-122.full
Mat-forming Quillwort (Isoetes tegetiformans) https://www.georgiabiodiversity.org/portal/profile?group=plants&es_id=20422
Mountain Bog Quillwort (Isoetes valida) https://www.jstor.org/stable/1547604?seq=1#metadata_info_tab_contents
Seasonally or permanently flooded sands and silty sands along small streams in mature swamps with few other associated plants.
Quillworts are seedless, non-flowering plants that reproduce by spores. Quillworts have a short, fleshy, rootstock called a corm; leaves are produced on the upper surface of the corm, roots on the lower surface. The leaves wither during dry periods; however, the corm remains alive and will begin to produce leaves when there is adequate water. The leaves have hollow chambers at the base where two types of spores are produced: tiny, dust-sized microspores develop sperm-producing structures, and larger (though still minute) megaspores produce eggs. Sperm swim to the eggs in available water and unite to form new plants. Quillworts compete poorly with other aquatic plants and are typically found in relatively sterile sand or silt or in frequently water-worn sites that support few or no other vascular plants.
Surveys are best conducted in late spring–early summer when plants are most conspicuous and leaves have not withered; mature megaspores are best developed in mid–late summer but can usually be found (from previous years’ growth) in the soil at the base of plants in the spring.
Five counties in the vicinity of Tifton in the Coastal Plain of Georgia.
Ditching, draining, and filling in of wetlands, impounding streams, clearcutting in swamps and floodplains, trash dumping in wetlands.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Agriculture & aquaculture | Energy production & mining | Transportation & service corridors |
| Specific Threat | None | None | None |
Isoetes georgiana is ranked S2? by the Georgia Department of Natural Resources, indicating that the species is probably imperiled in Georgia. Thirteen populations have been documented but only two have confirmed in the last 20 years; none occur on conservation land.
Protect floodplains and swamps from damming, clearing, draining, and filling; maintain water quality (including existing nutrient and water temperature conditions) within local watersheds.
Brunton, D.F. 2015. Key to the quillworts (Isoëtes: Isoëtaceae) of the southeastern United States. American Fern Journal 105(2): 86-100. https://www.jstor.org/stable/44076059?seq=1#metadata_info_tab_contents
Brunton, D.F. and D.M. Britton. 1996. The status, distribution, and identification of Georgia quillwort (Isoetes georgiana, Isoetaceae). American Fern Journal 86: 105-113. https://www.jstor.org/stable/1547149?seq=1#metadata_info_tab_contents
GADNR. 2020. Element occurrence records for Isoetes georgiana. Georgia Department of Natural Resources, Wildlife Resources Division, Social Circle, Georgia.
Luebke, N.T. 1992. Three new species of Isoetes from the southeastern United States. American Fern Journal 82(1): 23-26. https://www.jstor.org/stable/1547757?seq=1#metadata_info_tab_contents
Musselman, L.J. 2001. Georgia quillworts. Tipularia, Journal of the Georgia Botanical Society 16: 2-19, and 40.
NatureServe. 2019. Isoetes georgiana comprehensive report. NatureServe Explorer. Arlington, Virginia. http://explorer.natureserve.org/servlet/NatureServe?searchName=Isoetes+georgiana
Taylor, W.C., N.T. Luebke, D.M. Britton, R.J. Hickey, D.F. Brunton. 1993. Isoëtes boomii species account. Flora of North America, Vol. 2. Oxford University Press, New York. http://beta.floranorthamerica.org/Iso%C3%ABtes_georgiana
Weakley, A.S. 2015. Flora of the southern and mid-Atlantic States. University of North Carolina Herbarium, University of North Carolina, Chapel Hill. http://www.herbarium.unc.edu/flora.htm
Linda G. Chafin and Daniel F. Brunton
L. Chafin and D. Brunton, Dec. 2008: original account.
K. Owers, Feb. 2010: added pictures.
L. Chafin, March 2020: updated original account.
