CPC National Collection Plant Profile

Isoetes louisianensis

Suzzanne Chapman

Heading for profile page
CPC Home Join now
About CPC
CPC National Collection
Conservation Directory Resources
Invasive Plant Species Plant News
Plant Links Participating Institutions
Search CPC
Search    Alphabetical List    Reference Finder    CPC Home

CPC National Collection Plant Profile

Isoetes louisianensis

Common Name: 
Louisiana quillwort
Growth Habit: 
CPC Number: 


Profile Links
 Fish & WildLife
 Forest Service

Isoetes louisianensisenlarge
Photographer: Suzzanne Chapman
Image Owner: Mercer Arboretum and Botanic Gardens

Isoetes louisianensisenlarge
Photographer: Suzzanne Chapman
Image Owner: Mercer Arboretum and Botanic Gardens

Isoetes louisianensis is Partially Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 
Dave Berkshire contributed to this Plant Profile.

Isoetes louisianensis

Quillworts, relatives of ferns, live in or near lakes or streams, especially those with low nutrient content. Lacking stomata, quillworts take in carbon dioxide from the soil and collect the gas in four long, cylindrical air chambers inside their leaves. Quillworts are primitive, seedless vascular plants and reproduce by spores. The sporangia (spore-containing structures) are found inside the broadened bases of the 6-16 inch-long leaves of these "living fossils".

The Louisiana quillwort is thought to be one of the rarest quillworts in North America and inhabits cool, clear creeks and roots in sand and gravel a few inches to a few feet under water. It appears to be dependent on small springs to provide water flow during dry seasons.

Distribution & Occurrence

State Range
State Range of  Isoetes louisianensis
  Occurs on sand and gravel bars, overflow channels, and areas in or near shallow, blackwater streams in riparian woodland and bayhead forests of pine flatwoods and upland pine forests. (USFWS 1996

Louisiana Quillwort is associated with Viola primulifolia (Primrose-leafed Violet), Scirpus divaricatus (Bullrush), Justicia lanceolata (Water-willow, Hypoxis leptocarpa (Yellow-star Grass), Xyris species (Yellow-eyed Grass) and Carex species (Sedge), Nyssa sylvatica var. biflora (Swamp Tupelo), Nyssa aquatica (Water Tupelo), Magnolia virginiana (Sweetbay), Taxodium distichum (Baldcpress), Quercus obtusa (Swamp Laurel Oak), Acer rubrum (Red Maple), Pinus taeda (Loblolly Pine), Cyrilla racemiflora (Ti Ti), Lyonia lucida (Fetterbush) and Ilex verticillata (Winterberry).

  This aquatic plant has been reported along the rivers and streams in St. Tammany and Washington parishes in Louisiana and in Jackson and Perry counties in Mississippi within the Gulf Coastal Plain physiographic province. (USFWS 1996)

Number Left
  Currently known from ~10 sites in St. Tammany and Washington parishes in southeastern Louisiana as reported by the Louisiana Natural Heritage Program in January 2002 (Patricia Faulkner, 2002):
• Site 1 – last observation 2001; 3 populations – first still in tact, plants not counted, but original count listed 2600 plants, second group 20 plants, and third group 270 plants down from 335.
• Site 2 – last observation 1997, 4 plants reported; not searched in 2001 survey – ownership questionable, no access
• Site 3 – last observation 2001; 83 plants found near bridge in one population, another population reported in 1997 in same area 335 plants probably still intact.
• Site 4 – last observation 2001; 2000-2500 plants in sweetgum wetland.
• Site 5 – last observation 1997; 50 plants; habitat now considered marginal
• Site 6 – last observation 1997; 25 plants in brushy streamside where timber had been harvested.
• Site 7 – last observation 2001; no plants found and habitat deteriorated; original population of 18 plants in 1997
• Site 8 – last observation 1997; 20 plants.
• Site 9 – originally identified as I. louisianensis, but later (1997) tentatively identified as I. melanopoda.
• Site 10 – last observation 2001; near Abita Creek Preserve owned by The Nature Conservancy; total 800 plants.

USFWS (1996) report occurrences in two counties in southern Mississippi: Jackson and Perry counties:
• Jackson County, DeSoto National Forest, Red Creek Wildlife Management Area, Tchoutacabouffa River watershed:
Site 1 - ~50 plants in overflow channels of a streamhead
• Perry County, DeSoto National Forest, Camp Shelby National Guard Training Site, Pascagoula River Watershed:
Site 2 - ~2,500 plants in five colonies along a 1.0 mile stretch near the headwaters of a creek
Site 3 - ~1,500 plants in scour channels mainly along a 0.2 mile stretch of a small tributary
Site 4 - ~20 plants near an intermittent stream draining into a creek


Global Rank:  
Guide to Global Ranks
Federal Status:  
Guide to Federal Status
Recovery Plan:  

State/Area Protection
  State/Area Rank Status Date  
  Louisiana S2 2/11/1991  
  Mississippi S2  

Conservation, Ecology & Research

Ecological Relationships
  Quillworts, relatives of ferns, live in or near lakes or streams, especially those with low nutrient content. Lacking stomata, quillworts take in carbon dioxide from the soil and collect the gas in four long, cylindrical air chambers inside their leaves.

  • Timber harvest leading to erosion and runoff.
• Gravel mining significantly transforms riparian forest communities and alters stream quality and dynamics and poses serious threat to populations.
• Dredging, ditching, channelization, road construction.
• Off-road vehicles, which alter natural processes and result in habitat loss.
• Feral hog activity.
• Beaver dams alter riparian habitats.
• Over-collection of plants
(USFWS 1996)

Current Research Summary
  • Tissue culture and cryopreservation research is ongoing at Cincinnati Zoo and Botanical Garden Center for Research of Endangered Wildlife by Dr. Valerie Pence. Dr. Pence is developing protocols for tissue culture and cryopreservation of this species under "Tissue Culture Propagation of Selected Species in the National Collection of Endangered Plants" (Institute of Museum and Library Services grant) from plants in propagation at Mercer Arboretum and Botanic Gardens.
• Protocols for the long-term storage of spores, etc. have not been established. Propagation techniques for Isoetes are referenced to researchers including Garrie Landry and Dr. Neil Luebke.
• Plants received from one site from Washington Parish in Louisiana in 1991 by Mercer Arboretum and Botanic Gardens prefer cool, semi-aquatic conditions in our shade nursery. Plants are grown in shallow tubs on saucers in cool (at ground level), shade conditions and prefer an acidic sand-peat substrate. In addition, sixty-nine plants were received from the Louisiana Natural Heritage Office, Baton Rouge, in April 2002 as a rescue from a bridge construction site in St. Tammany Parish. These plants are thriving in Mercer's conservation nursery. These plants will be reintroduced near the collection site following restoration of the area in 2003 or 2004.
• Mercer’s off-site Conservation Area provides secure, raised beds for mass propagation of plants. Each bed within the Conservation Area is provided with independently controlled irrigation and contains propagation substrates that meet the unique requirements for each species. Beds for wetlands species are lined to provide aquatic conditions. Isoetes louisianensis plants can be maintained/produced in mass within Mercer’s Conservation Area, in addition to those currently maintained in our Nursery, for reintroductions and restorations.
• The Endangered Species Garden, established in 1994 with support from Star Enterprises, displays rare native plants for the public to view year-round. In Spring 2002, the River Oaks Garden Club of Houston, TX provided a generous gift to initiate the expansion and renovation of Mercer’s Endangered Species Garden. This expansion and renovation will include a stream habitat and will provide a permanent educational display habitat for the Louisiana Quillwort.
• Mercer maintains a permanent bank of rare seeds and plants collected from field surveys and from propagation work. Mercer also banks subsets of rare seeds or plants with our collaborating CPC institutions and with the National Center for Genetic Resources Preservation (NCGRP) in Ft. Collins, CO (formerly called the National Seed Storage Laboratories).

Current Management Summary
  • Conservation measures have been taken to preserve the health of a number of locations where this species occurs (USFWS 1996).

Research Management Needs
  • Research the basic biology of this species.
• Continued analysis of the genetics of this species.
• Rescue of threatened populations.
• Identify secure reintroduction sites.

Monitoring Efforts
  Not Available

Ex Situ Needs
  • Expand gene bank.
• Propagation protocols for spores.
• Maintain rescued populations for reintroductions.


Journal Articles

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

Landry, G.; Thieret, J.W. 1971. Notes. Sida. 5, 2: 129-130.

Landry, G.; Thieret, J.W. 1973. Isoetes louisianensis (Isoetaceae)., a new species from Louisiana. Sida. 5, 2: 129-130.

Sorrie, B.A.; Leonard, S.W. 1999. Noteworthy Records of Mississippi Vascular Plants. Sida. 18, 3: 889-908.

USFWS. 1976. Proposed Endangered Status for 1700 U.S. Plants. Federal Register. 41: 24523-24572.

USFWS. 1991. Proposed endangered status for the plant Isoetes louisianensis (Louisiana quillwort). Federal Register. 56, 205: 52500-52503.

USFWS. 1992. Determination of endangered status for the plant Isoetes louisianensis (Louisiana quillwort). Federal Register. 57, 209: 48741-48747.

USFWS. 1992. Final Listing Rules Approved for 21 Species During July/October 1992. Endangered Species Technical Bulletin. 17, 9-11: 9.


Faulkner, P. 1999. Rare Plant Species of Louisiana. Louisiana Natural Heritage Program.

Kral, R. 1983. A report on some rare, threatened, or endangered forest-related vascular plants of the South. Athens, GA: U.S. Dept. of Agriculture Forest Service. p.1305. U.S. Dept. of Agriculture Forest Service Technical.

Larke, J. 1997. Status Survey Report for Isoetes louisianensis Thieret in Louisiana. Jackson, Mississippi: U.S. Fish & Wildlife Service. p.11.

McInnis, N.C. 1991. Status Survey for Isoetes louisianensis Thieret. Arlington, Virginia: Report to the Nature Conservancy. p.7.

USFWS. 1996. Recovery plan for Louisiana quillwort (Isoetes louisianensis Thieret). Atlanta, Georgia: U.S. Fish & Wildlife Service, Endangered Species Office. p.26.

  This profile was updated on 3/4/2010
New Mexico
North Dakota
South Dakota
South Carolina
North Carolina
West Virginia
New Jersey
Rhode Island
New Hampshire
New York
New York