Isoetes louisianensis

Species:Isoetes louisianensis Thieret
Common Name:Louisiana Quillwort
Associated Ecological Communities:**
Growth Habit:Herb
USDA Symbol:**
Plant Notes:Louisiana Quillwort is a native seedless vascular plant in the Quillwort family (Isoetaceae). It is native to Alabama, Mississippi, and Louisiana. It Alabama it is known to occur in two counties in southwest Alabama. It grows in shallow water and low muddy areas near streams. Louisiana Quillwort is a perennial from a corm (a fleshy underground stem). The corm is globose in outline and two-lobed. Roots are produced from the base of the corm and leaves (microphylls) from the upper portion. The leaves are spirally arranged, hollow, and transversely septate. The leaves are linear and taper gradually to a pointed tip. Leaves are glabrous and bright green in color. Some leaves contain sporangia at their base. These leaves are known as sporophylls. The sporangium is covered by a flap of tissue called a velum. The velum covers less than half of the sporangium. Louisiana Quillwort is heterosporous—producing two kinds of spores. Megaspores are larger and white in color. The surface of the megaspore is cristate with thick ridges. Smaller spores known as microspores are brown in color with a spinulose surface. Louisiana Quillwort was listed as an Endangered Species by the US Fish and Wildlife Service on October 28, 1992. In Alabama, it is listed as a S1 species (typically 5 or fewer occurrences, very few remaining individuals, acres, or miles of stream, or some factor of its biology making it especially vulnerable in the state), and globally it is listed as a G2 species (imperiled globally because of rarity (6 - 20 occurrences, or few remaining acres, or miles of stream) or very vulnerable to extinction throughout its range because of other factors).--A. Diamond
Taxonomic Notes:Listed as Federally Endangered as of 28 Oct 1992.
Status:Native, Endangered-US, S1 (State Rank), G2 (Global Rank)
Specimen: View specimen details in the Alabama Herbarium Consortium Specimen Database

** Not applicable or data not available.


FamilyISOETACEAE - Quillwort family
Genus Isoetes
Species Isoetes louisianensis Thieret - Louisiana Quillwort


Citation Isoetes louisianensis Thieret, Sida 5: 129. 1973.Isoetes louisianensis Thieret, Sida 5: 129. 1973.
Basionym: **
Type: LOUISIANA. Washington Par.: in and along Thigpen Creek 1 mile E of Enon, 21 Apr 1972. John W. Thieret 33660. (Holotype: GH; isotype: MICH).

** Not applicable or data not available.


No synonyms exist for this species.

Specimens and Distribution

This species has been reported in the following counties by the herbaria listed. An overview of the individual specimens are provided in the table that follows. Click on the accession number to view details; click on column headers to sort; choose a county or herbaria to filter the specimen data.

Counties included on distribution map: Butler, Conecuh, Monroe

Counties represented by specimen data listed below:

Herbaria represented by specimen data listed below: ALNHS, AMAL, TROY

Range of years during which specimens were collected: -

Barcode / Accession No. County Coll. Date Collector &
Collection No.
Herbarium &
Herbarium Name Used
TROY000028060 Monroe 16 May 2009 Diamond, Alvin R.
Isoetes louisianensis Thieret
AMAL00019595 Monroe 03 May 2012 Barger, T. Wayne
Isoetes louisianensis Thieret
TROY000000219 Conecuh 16 Mar 2000 Brunton, Daniel F.
Isoetes louisianensis Thieret
ALNHS00001124 Butler 03 May 2012 Barger, T. Wayne
Isoetes louisianensis Thieret
ALNHS00001212 Monroe 03 May 2012 Barger, T. Wayne
Isoetes louisianensis Thieret
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