''Isoetes louisianensis'', the Louisiana quillwort, is a small, grass-like aquatic plant of the family

Isoetaceae Isoetaceae is a family including living quillworts (''Isoetes'') and comparable extinct herbaceous lycopsids (''Tomiostrobus ''Tomiostrobus'' is an extinct quillwort genus from the Early Triassic of Australia, China and Russia, which was espe ...

. It is "one of the rarest

quillwort ''Isoetes'', commonly known as the quillworts, is the only extant genus of plants in the family Isoetaceae, which is in the class of lycopods. There are currently 192 recognized species, with a cosmopolitan distribution but with the individual s ...

s in North America."''I. louisianensis''.
Center for Plant Conservation. It occurs in only five locations in St. Tammany and Washington Parishes of

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

and some spots in southern

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

(United States). It is federally listed as an endangered species, partly due to its highly restricted range.USFWS
Determination of Endangered Status for the Plant ''Isoetes louisianensis'' (Louisiana Quillwort).
''Federal Register'' October 28, 1992. The Louisiana quillwort occurs predominantly on sand and gravel bars on small to medium-sized streams. These plants live for periods underwater. They are regularly inundated as much as 50 centimeters (20 inches) following rains, and may be inundated for long periods in wet seasons. Its

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

follows roughly along the Bogue Chitto River. Associated plants include primrose-leafed violet (''Viola primulifolia''),

bulrush Bulrush is a vernacular name for several large wetland grass-like plants *Sedge family (Cyperaceae): **''Cyperus'' **'' Scirpus'' **''Blysmus'' **''Bolboschoenus'' **'' Scirpoides'' **'' Isolepis'' **'' Schoenoplectus'' **'' Trichophorum'' * T ...

(''Scirpus divaricatus''), water-willow (''Justicia lanceolata''), yellow-star grass (''Hypoxis leptocarpa''), yellow-eyed grass ''Xyris'' sp. and

sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus '' Carex'' ...

(''Carex'' sp.), swamp tupelo (''Nyssa sylvatica'' var. ''biflora''),

water tupelo ''Nyssa aquatica'', commonly called the water tupelo, cottongum, wild olive, large tupelo, tupelo-gum, or water-gum, is a large, long-lived tree in the tupelo genus ''(Nyssa)'' that grows in swamps and floodplains in the Southeastern United Sta ...

(''Nyssa aquatica''), sweetbay (''Magnolia virginiana''),

bald cypress ''Taxodium distichum'' (bald cypress, swamp cypress; french: cyprès chauve; ''cipre'' in Louisiana) is a deciduous conifer in the family Cupressaceae. It is native to the southeastern United States. Hardy and tough, this tree adapts to a wide ...

(''Taxodium distichum''), swamp laurel oak (''Quercus obtusa''),

red maple ''Acer rubrum'', the red maple, also known as swamp maple, water maple, or soft maple, is one of the most common and widespread deciduous trees of eastern and central North America. The U.S. Forest Service recognizes it as the most abundant nativ ...

(''Acer rubrum''), loblolly (''Pinus taeda''), ti ti (''Cyrilla racemiflora''), fetterbush (''Lyonia lucida''), and

winterberry ''Ilex verticillata'', the winterberry, is a species of holly native to eastern North America in the United States and southeast Canada, from Newfoundland west to Ontario and Minnesota, and south to Alabama. Other names that have been used incl ...

(''Ilex verticillata''). Distinctive characteristics of this species include brown-spotted sporangial walls and mega spores with highly reticulate ridges, producing a spiny effect. The leaves are up to 40 cm long. The Louisiana quillwort was described recently, in 1973, and was listed as an endangered species in 1992.

References

External links

USDA Plants Profile
{{Taxonbar, from=Q6085661 louisianensis Endangered plants Plants described in 1973 Flora of North America