naiad, water nymph
Najas graminea, N. marina, and N. minor have been introduced in numerous countries.
Najas graminea and N. marina are troublesome weeds in irrigation canals in numerous countries.
Perennial or annual, obligate submerged, attached. Monoecious or dioecious. Stems slender, much-branched. Leaves alternate, appearing whorled or clustered, linear; base with distinctive dilated sheath; margin serrate to toothed. Inflorescence inconspicuous. Flowers axillary, solitary or clustered, sessile, unisexual. Dispersal by stem fragments or seed.
all types of water bodies
Najas are slender plants, often brittle and frequently forming large monoclonal stands. The genus contains ca. 40-50 species worldwide and is occasionally cultivated for aquaria.