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.



Perennial, rooted in mud, submersed or floating, dioecious (CA plants staminate)
Stem slender, sometimes branched or not
Leaves opposite below, crowded and whorled above, 3–6 per whorl, sessile
Staminate inflorescence: flowers 2–3, clustered, peduncled; bract slender
Pistillate inflorescence: flower 1, axillary; bract slender, ± tubular
Staminate flower floating; perianth tube elongated, slender, peduncle-like, persistent on plant; stamens 9
Pistillate flower floating; perianth tube elongated, slender, peduncle-like, persistent on plant; stigmas 3, 3–4-lobed
Species in genus: 2 species: South America
Etymology: (Latin: a mythical water nymph)


E. densa Planch.

Stem 2–3 mm thick
Leaf 2–4 cm, 2–5 mm wide, narrowly oblong; margin finely serrate
Staminate flower: perianth tube < 6 cm; petals 8–10 mm, white, ± round
Pistillate flower: perianth tube < 6 cm; petals 6–7 mm, white, ± round
Chromosomes: 2n=48
Ecology: Streams, ponds, sloughs
Elevation: < 2200 m.
Bioregional distribution: n&s Sierra Nevada Foothills, San Joaquin Valley, San Francisco Bay Area, San Jacinto Mountains, East of Sierra Nevada (expected elsewhere)
Distribution outside California: to e US, Europe; native to S.America
Flowering time: Jul–Aug
Staminate plants widely cultivated for aquaria
Synonyms: Elodea d. (Planch.) Casp

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bioregional map for EGERIA%20densa 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 Egeria densa
Retrieve dichotomous key for Egeria
Overlay Consortium of California Herbaria specimen data by county on this map
Show other taxa with the same California distribution | Read about bioregions | Get lists of plants in a bioregion
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