Jepson Flora Project: Jepson Interchange    

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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California
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Robert F. Thorne

Annual, perennial herb, aquatic, freshwater or marine, bisexual, monoecious, or dioecious
Leaves basal or cauline, alternate, opposite, or whorled, generally ± sheathing at base, glabrous
Inflorescence: cyme; flowers 1–few, subtended by ± sheathing, entire or lobed bract; staminate flowers sometimes deciduous, free-floating
Flower radial; perianth tube 0 or much elongated, peduncle-like in flower; sepals (0)3, green; petals (0)3, colored or white; stamens (1)3–many, generally in 1+ series; ovary inferior, chamber 1, placentas parietal or basal, ovules 1–many; style lobes generally 3, linear, lobed or notched
Fruit: achene or berry-like and dehiscing irregularly, linear to spheric, submersed
Genera in family: ± 17 genera, ± 130 species: worldwide; some cultivated for aquaria, others noxious weeds.


Annual, aquatic, submersed, sometimes mat-like, monoecious or dioecious
Stems several, much-branched, slender
Leaves simple, cauline, opposite or appearing ± whorled; sheath generally wider than blade, expanded abruptly at junction with blade; blade generally linear, margin entire to spiny
Inflorescence axillary; flowers 1–few, clustered, inconspicuous
Staminate flower: perianth 0; stamen 1, anther opening irregularly, subsessile, subtended by 2 minute involucres, inner membranous, flask-shaped, outer cup-like, tubular, or with free scales
Pistillate flower: perianth part 0–1; ovary 1, chamber 1, ovule 1, style short, stigmas 2–4, linear
Fruit: achene, fusiform; outer wall thin, ± translucent
Species in genus: ± 50 species: ± worldwide
Etymology: (Greek: water nymph)
Reference: [Shaffer-Fehre 1991 Bot J Linn Soc 107:189–209]


N. flexilis (Willd.) Rostk. & Schmidt


Stem < 20 dm, much-branched
Leaves 1–2.5 cm, 1–2 mm wide, crowded on distal branches, flexible; sheath obtuse at junction with blade; blade margin minutely toothed, tip narrowly long-tapered
Staminate flower 2.5–3 mm; anther 1-chambered
Pistillate flower ± 3 mm; stigmas generally 3, sometimes 2–4
Fruit: surface smooth, shiny (finely net-like at 20X magnification)
Ecology: Uncommon. Ponds, lakes
Elevation: < 1500 m.
Bioregional distribution: Klamath Ranges, Inner North Coast Ranges (expected elsewhere)
Distribution outside California: to Canada, ne US, n Europe

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bioregional map for NAJAS%20flexilis being generated
YOU CAN HELP US make sure that our distributional information is correct and current. If you know that a plant occurs in a wild, reproducing state in a Jepson bioregion NOT highlighted on the map, please contact us with that information. Please realize that we cannot incorporate range extensions without access to a voucher specimen, which should (ultimately) be deposited in an herbarium. You can send the pressed, dried collection (with complete locality information indicated) to us (e-mail us for details) or refer us to an accessioned herbarium specimen. Non-occurrence of a plant in an indicated area is difficult to document, but we will especially value your input on those types of possible errors (see automatic conversion of distribution data to maps).

Retrieve Jepson Interchange Index to Plant Names entry for Najas flexilis
Retrieve dichotomous key for Najas
Overlay Consortium of California Herbaria specimen data by county on this map
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