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Isoetes hyemalis D.F. Brunton
Winter Quillwort
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G2G3
State Rank: S1?
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: Highest Conservation Concern
Element Occurrences (EOs) in Georgia: 2
Habitat Summary for element in Georgia: Sandy blackwater creek banks; deciduous swamps
Perennial herb, forming robust tufts of leaves on creek banks. The rootstock (corm) with two lobes, one or more attached to a knotty, horizontal, underground stem (rhizome); new plants develop from these corms. The leaves are 9 - 10.6 inches (23 - 27 cm) long, evergreen, bright green when young, dark brownish-green when older, flared at the base and tapering to a sharply pointed tip, with 4 cross-walls and a single midvein; when growing in flowing water, the leaves are long, wavy, and slightly curled. Spores are produced in the sporangium, a brown-streaked or brown-spotted chamber 0.2 inch (5.3 mm) long in the leaf base, with a transparent membrane (velum) covering 10 - 20% of the chamber opening. Dozens of tiny, grayish-white female spores (megaspores), approximately 0.05 mm across and covered with a dense pattern of bumps (low spines) and very short, loosely connecting ridges, may be seen with 20 - 30x magnification. Olive-gray to tan, 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 flared base of the leaves.
Engelmann’s Quillwort (Isoetes engelmannii) has long leaves (10 - 24 inches, 25 - 60 cm) like winter quillwort, and the velum covers less than 30% of the sporangia, but it has lighter green leaves and smaller megaspores with regularly reticulate ornamentation patterns; Engelmann’s quillwort is the most common quillwort in Georgia but is found mostly in the Piedmont.
Appalachian Quillwort (Isoetes appalachiana), found across the state, has the same size megaspores as winter quillwort but these have an irregularly reticulate ornamentation pattern.
Southern Quillwort (Isoetes flaccida) also occurs in the southwest portion of Georgia’s Coastal Plain in habitats similar to winter quillworts; it also has long leaves (4 - 24 inches, 10 - 60 cm) but its velum completely covers the spore chamber, which is colorless (not streaked with brown), and contains smaller, more plainly ornamented megaspores.
Boom’s Quillwort (Isoetes boomii) and Georgia Quillwort (I. georgiana) both have larger, more coarsely ornamented megaspores and more extensive velum coverage.
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
Densely shaded blackwater creeks with circumneutral to basic water pH, sandy banks along seasonally flowing streams, and flowing water in swamps. Outside of Georgia, Winter Quillwort forms pure stands of several hundred plants in blackwater streams, but also may occur with rushes (Juncus), pondweeds (Potamogeton), and burweed (Sparganium americanum).
Quillworts are seedless, non-flowering plants that reproduce by spores. Winter quillwort also may rarely reproduce vegetatively by producing plantlets along a horizontal, underground rhizome. Quillwort leaves have hollow chambers at the base where two types of spores are produced: tiny 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 in Georgia are best conducted in late spring – early summer when plants are most conspicuous and their leaves have not withered; mature megaspores are best developed in mid – late summer but may be found (from previous year’s growth) in the soil at the base of plants during the following spring.
Coastal Plain and lower Piedmont of Georgia, Florida, Alabama, South Carolina, North Carolina, and Virginia.
Ditching and draining wetlands, impounding streams, clearcutting in swamps and floodplains. Invasion by exotic pest plants.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Transportation & service corridors | Biological resource use | Human intrusions & disturbance |
| Specific Threat | None | None | None |
Isoetes hyemalis is ranked S1? by the Georgia Department of Natural Resources, indicating that the species is probably critically imperiled in the state, but that additional information is needed to make a final ranking. Two populations have been documented in Georgia though neither have been confirmed since 2000; neither population occurs on conservation land.
Protect floodplains and swamps and adjacent areas of local watersheds from damming, clearing, draining, and filling. Eradicate exotic pest plants.
Brunton, D.F. 2015. Key to the quillworts (Isoetes: Isoetaceae) 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., D.M. Britton, and W.C. Taylor. 1994. Isoetes hyemalis, sp. nov. (Isoetaceae): a new quillwort from the southeastern United States. Castanea 59: 12-21. https://www.jstor.org/stable/4033758
GADNR. 2020. Element occurrence records for Isoetes hyemalis. Georgia Department of Natural Resources, Wildlife Resources Division, Social Circle, Georgia.
Musselman, L.J. 2001. Georgia quillworts. Tipularia, Journal of the Georgia Botanical Society 16: 2-19, 40.
NatureServe. 2019. Isoetes hyemalis comprehensive report. NatureServe Explorer. Arlington, Virginia. http://explorer.natureserve.org/servlet/NatureServe?searchName=Isoetes+hyemalis
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.
