Isoetes louisianensis

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." It occurs in only five locations in St. Tammany and Washington Parishes of Louisiana, as well as some spots in southern Mississippi and south-central Alabama. It is federally listed as an endangered species, partly due to its highly restricted range. 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. Associated plants include primrose-leafed violet (Viola primulifolia), bulrush (Scirpus divaricatus), water-willow (Justicia lanceolata), yellow-star grass (Hypoxis leptocarpa), yellow-eyed grass Xyris sp. and sedge (Carex sp.), swamp tupelo ......read more on Wikipedia.