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Aquatic and Wetland Vascular Plants of the Northern Great Plains

Najas L. -- Naiad


Small, submersed, monoecious or dioecious, perennial herbs; stems flexuous, freely branched, anchored by roots. Leaves simple, opposite, sessile, abruptly broadened at the base to sheath the stem, the margins faintly to coarsely toothed. Flowers minute, imperfect, solitary and sessile in the leaf axils, enclosed by the sheathing leaf bases; male flowers consisting of a single anther enclosed in a membranous envelope, this in turn surrounded by a firmer, entire to 4-lobed, perianthlike structure; female flowers comprised of a single, 1-ovuled pistil, stigmas 2-4, style usually elongate and persistent. Fruit a fusiform achene, the pericarp thin and easily removed to expose the single ellipsoid seed.

Reference:

Clausen, R. T.  1936.  Studies in the genus Najas in the
     northern United States.  Rhodora 38:333-345.

Lead Characteristic Go To
1 Leaves coarsely spinulose-toothed; seeds 4-5 mm long. N. marina
1 Leaves very faintly toothed; seeds 2-3 mm long. Lead 2
2 Seed coat (under the thin pericarp) shiny, very faintly reticulate, with 30-40 rows of obscure pits across the middle; style beak of achene 1 mm or more long. N. flexilis
2 Seed coat rather dull, coarsely reticulate, with 10-20 rows of pits across the middle; style beak of mature achene 0.5 mm or less long. N. guadalupensis


57. Najadaceae, the Naiad Family
1. Najas L. -- Naiad
1. Najas flexilis (Willd.) Rostk. & Schmidt
2. Najas guadalupensis (Spreng.) Magnus. -- Southern naiad
3. Najas marina L.


Return to Family -- Najadaceae - The Naiad Family
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