Najas

Taxonomic status Accepted
Occurrence status Present
Origin Native
Degree of establishment Native

Submerged aquatic herbs, annuals or perennials, monoecious or dioecious, rooting from base and basal nodes. Stem and branches slender, fragile. Leaves linear, subopposite or pseudo-whorled, sessile; base sheathing; margin toothed; leaf-sheath scales 2, small, axillary (subtended by sheath). Flowers very small and inconspicuous, at base of branches, 1–4 together, unisexual. Male flowers enclosed by 2 cup-like structures, an outer whorl which is usually fused into a tube, and an inner whorl which is membranous, fused, flask-shaped and 2-lobed distally; stamen 1, sessile or almost so. Female flower with cup-like structure absent; carpel 1; ovary ellipsoid; style subconical to cylindric, stigmas 2–4, linear. Fruit dry, indehiscent, 1-seeded, style and stigmas persistent; seed oblong; testa hard and brownish.

Cosmopolitan genus of about 35 species, 2 in Victoria. Pollination takes place completely submerged. Elongation of the stalk of the anther ruptures the surrounding scale-tube. The pollen is released apically and is then transported through the water to the female flowers.

Najasis sometimes included in a monogeneric familiy Najadaceae.

Source:

Conn, B.J. (1994). Najadaceae. In: Walsh, N.G.; Entwisle, T.J., ‍Flora of Victoria Vol. 2, Ferns and Allied Plants, Conifers and Monocotyledons‍, pp. 155–156. Inkata Press, Melbourne.

Updated by: Andre Messina, 22 Jul. 2014
Najas (hero image) Spinning