Directory       News       Site Map       Home
    Jepson eFlora
Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.


Annual, aquatic, submersed, mat-like or not; monoecious or dioecious. Stem: several, often much-branched, slender. Leaf: simple, cauline, ± opposite to ± whorled, sessile; sheath generally wider than, expanded abruptly at junction with blade; blade generally linear, margin entire to coarsely spine-toothed. Inflorescence: axillary; flowers 1–few, clustered, inconspicuous. Staminate flower: subtended by (0)2 minute involucres, inner membranous, flask-shaped, outer cup-like, tubular, or with free scales; perianth 0; stamen 1, anther opening irregularly, subsessile. Pistillate flower: generally not subtended by involucres; perianth 0; ovary 1, chamber 1, ovule 1, style short, generally terminal (from center of ovary, fruit top), stigma 2–4-lobed. Fruit: achene-like, fusiform; outer wall thin, ± translucent.
± 50 species: ± worldwide. (Greek: water nymph) [Haynes 2000 FNANM 22:77–83] Najas graminea Delile is an agricultural weed.
Unabridged references: [Shaffer-Fehre 1991 Bot J Linn Soc 107:189–209; Haynes 2000 FNANM 22:77–83]

Key to Najas

1. Staminate, pistillate flowers on different plants; leaf blade midrib abaxially prickled; internodes generally prickled; seed >= 1.2 mm wide, coat pitted ..... N. marina

1' Staminate, pistillate flowers on same plants; leaf blade midrib abaxially not prickled; internodes not prickled; seed <= 1.2 mm wide, coat smooth or pitted, smooth if seed reaching 1.2 mm wide

2. Style subterminal (not from center of ovary, fruit top) ..... N. gracillima

2' Style terminal

3. Seed narrowly to widely obovate, coat smooth, shiny; anther chambers 1 ..... N. flexilis

3' Seed fusiform, coat pitted, dull; anther chambers 4 ..... N. guadalupensis subsp. guadalupensis


Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
We encourage links to these pages, but the content may not be downloaded for reposting, repackaging, redistributing, or sale in any form, without written permission from The Jepson Herbarium.