Scientific name

Najas L.

Common names

naiad, water nymph



Native distribution


Species commonly cultivated

Najas conferta (A. Braun) A. Braun (Americas)

N. graminea Delile (cosmopolitan)

N. guadalupensis (Spreng.) Magnus (Americas)

N. indica (Willd.) Cham. (Asia)

N. marina L. (cosmopolitan)

Adventive distribution

Najas graminea, N. marina, and N. minor have been introduced in numerous countries.

Weed status

Najas graminea and N. marina are troublesome weeds in irrigation canals in numerous countries.


submersed, much-branched stem plant

Brief description

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.

Natural habitat

all types of water bodies

Additional comments

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.