Jepson eFlora: Taxon page
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Egeria densa

Higher Taxonomy
Family: HydrocharitaceaeView DescriptionDichotomous Key

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.
Genus: EgeriaView Description 

Habit: Perennial herb, submersed, rooted in mud; dioecious. Stem: slender, branched or not. Leaf: opposite below, crowded and in whorls of 3--6 above, sessile, finely to coarsely serrate. Staminate Inflorescence: axillary, sessile; flowers 2--4(5), 1 open at a time; bract slender. Pistillate Inflorescence: [axillary, sessile; flower 1; bract slender, +- tubular]. Staminate Flower: floating; pedicel elongate, peduncle-like, persistent on pl; stamens 9. Pistillate Flower: [floating; perianth tube elongate, peduncle-like; stigmas 3, 3--4-lobed].
Species In Genus: 2 species: South America. Etymology: (Latin: mythical water nymph) Note: Only staminate plants observed outside native range. Egeria najas Planch. expected but not yet found.

Egeria densa Planch.
Stem: 2--3 mm thick. Leaf: 1.2--4 cm, 2--5 mm wide, recurved, narrowly oblong, finely serrate. Staminate Flower: pedicel <= 8 cm; petals 8--10 mm, white, +- round. Pistillate Flower: [as staminate; petals 6--7 mm]. Chromosomes: 2n=46.
Ecology: Streams, ponds, sloughs; Elevation: < 2200 m. Bioregional Distribution: SNF, GV, SnFrB, SnJt, GB; Distribution Outside California: to eastern United States; Europe; native to South America. Flowering Time: Jul--Aug Note: Staminate plants widely cultivated for aquaria.
Synonyms: Elodea densa (Planch.) Casp.
eFlora Treatment Author: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes
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botanical illustration including Egeria densa


Citation for this treatment: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes 2016. Egeria densa, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on May 05, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on May 05, 2016.

Egeria densa
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© 2009 Barry Rice

More photos of Egeria densa in CalPhotos

Geographic subdivisions for Egeria densa:
SNF, GV, SnFrB, SnJt, GB;
Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.