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Vascular Plants of California
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Najas

Higher Taxonomy
Family: HydrocharitaceaeView DescriptionDichotomous Key

Common Name: WATERWEED FAMILY
Habit: Annual, perennial herb, aquatic, freshwater or marine, glabrous or hairy; monoecious, dioecious, or flowers bisexual. Leaf: basal, alternate, opposite, or whorled, generally sessile, generally +- sheathing at base. Inflorescence: axillary, terminal, or scapose, cyme or flowers 1, subtended by +- sheathing, entire or lobed bract; staminate flowers sometimes deciduous, free-floating. Flower: generally radial; perianth 0 or tube 0 or elongate, peduncle-like in flower; sepals (0)3(4), green; petals (0)3(4), white or not; stamens (0)2--many, generally in 1+ series; ovary inferior, chamber 1 or falsely 6--9, placentas parietal, 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. Note: Ottelia alismoides (L.) Pers. is a possibly extirpated alien.
eFlora Treatment Author: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes
Scientific Editor: Thomas J. Rosatti.
Najas
Habit: 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.
Species In Genus: +- 50 species: +- worldwide. Etymology: (Greek: water nymph) Note: Najas graminea Delile is an agricultural weed.
Jepson eFlora Author: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes
Reference: Haynes 2000 FNANM 22:77--83
Unabridged Reference: Shaffer-Fehre 1991 Bot J Linn Soc 107:189--209; Haynes 2000 FNANM 22:77--83
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)
Key to Najas

Previous taxon: Limnobium spongia
Next taxon: Najas flexilis

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Citation for this treatment: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes 2012, Najas, in Jepson Flora Project (eds.) Jepson eFlora, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=9741, accessed on April 24, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora, https://ucjeps.berkeley.edu/eflora/, accessed on April 24, 2024.