''Isoetes louisianensis'', the Louisiana quillwort, is a small, grass-like aquatic plant of the family Isoetaceae. It is "one of the rarest quillworts in North America."''I. louisianensis''.
Center for Plant Conservation. It occurs in only five locations in

St. Tammany Tamanend (historically also known as Taminent, Tammany, Saint Tammany or King Tammany, "the Affable," ) (–) was the Chief of Chiefs and Chief of the Turtle Clan of the Lenni-Lenape nation in the Delaware Valley signing the Peace Treaty wit ...

and

Washington Parish Washington Parish (French: ''Paroisse de Washington'') is a parish located in the interior southeast corner of the U.S. state of Louisiana, one of the Florida Parishes. As of the 2010 census, the population was 47,168. Its parish seat is Fra ...

es of Louisiana and some spots in southern Mississippi (United States). It is federally listed as an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

, 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 follows roughly along the

Bogue Chitto River The Bogue Chitto River is a stream in the U.S. states of Louisiana and Mississippi. It is a tributary of the Pearl River. The river passes through the Bogue Chitto State Park in Washington Parish, Louisiana. ''Bogue Chitto'' is a name derived f ...

. Associated plants include primrose-leafed violet (''Viola primulifolia''), bulrush (''Scirpus divaricatus''), water-willow (''Justicia lanceolata''), yellow-star grass (''Hypoxis leptocarpa''),

yellow-eyed grass ''Xyris'' is a genus of flowering plants, the yelloweyed grasses, in the yellow-eyed-grass family. The genus counts over 250 species, widespread over much of the world, with the center of distribution in the Guianas. The leaves are mostly dis ...

''Xyris'' sp. and sedge (''Carex'' sp.),

swamp tupelo ''Nyssa biflora'', commonly referred to as the swamp tupelo, or swamp black-gum is a species of tupelo that lives in wetland habitats. Swamp tupelo grows chiefly in the coastal plains from Delaware, eastern Maryland, and southeastern Virginia, s ...

(''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''), swamp laurel oak (''Quercus obtusa''), red maple (''Acer rubrum''), loblolly (''Pinus taeda''), ti ti (''Cyrilla racemiflora''),

fetterbush Fetterbush is a common name for several plants in the family ''Ericaceae'', and may refer to: *''Leucothoe (plant), Leucothoe'' – several species including: **''Leucothoe fontanesiana'' (fetterbush) *''Pieris (plant), Pieris'' – several species ...

(''Lyonia lucida''), and winterberry (''Ilex verticillata''). Distinctive characteristics of this species include brown-spotted sporangial walls and mega

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s with highly reticulate ridges, producing a spiny effect. The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

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