Family: Salviniaceae Rchb.
Salvinia minima

Salvinia minima

Distribution: Basically tropical America from southern Mexico to Central America and South America to northern Argentina, Paraguay and Uruguay. It was introduced to southeastern part of USA, from South Carolina to New Mexico and California, sporadically in State of New York and Massachusetts.
Ecology: Fresh water fern found mostly in standing water, native to tropical America and invasive in southern states of US.
Description: Floating fern, deep green, stem about 6 cm, hairs dark. Leaves 1–1.5 cm, almost round to elliptic, obtuse or notched at tip, rounded to cordate at base, stiff, bifurcated hairs above, brown and pubescent below, slender unbranched hairs. Venation obscure, tips of veins free, ending short of margins. Sporocarps in clusters of 4–8, proximal sporocarps with up to 25 megasporangia, distal sporocarps with numerous microsporangia.
Salvinia minima
Salvinia minima
These images were taken in USA, Louisiana, Jean Lafitte National Park, Barataria Preserve (May 2014).