This vegetation type is dominated by Najas marina, a submerged aquatic species growing in dense stands on the bottom of still water bodies, and rarely of streams. It occurs mainly in man-made habitats in early successional stages such as fishponds and flooded sand pits. It occurs in mesotrophic to eutrophic, calcium-rich, often brackish water, which is on average deeper than that in sites with occurrences of N. minor (most often 0.4–1.2 m). This vegetation type occurs at scattered sites in the Czech lowlands and in colline landscapes.