Jepson eFlora: Taxon page
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Elodea bifoliata
TWO-LEAF WATERWEED

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.
Genus: ElodeaView DescriptionDichotomous Key

Habit: Perennial herb, rooting at nodes, submersed; dioecious or some flowers bisexual. Stem: slender, generally branched. Leaf: often 2 per node proximally, 3--7 distally, sessile, minutely serrate, midrib abaxially +- smooth. Inflorescence: axillary, sessile or not; flower 1; bract generally notched. Staminate Flower: floating, deciduous or not; perianth tube elongate, slender, peduncle-like; stamens 3--9. Pistillate Flower: floating; perianth tube elongate, slender, peduncle-like; style slender, stigmas 3, lobes 0 or 2. Fruit: cylindric to ovoid. Seed: several, smooth.
Species In Genus: +- 12 species: temperate, tropical America. Etymology: (Greek: of marshes)

Elodea bifoliata H. St. John
NATIVE
Leaf: generally not crowded at stem tips, 2 per node on lower stems, 2--3 on mid stems; blade generally 4.7--24.8 mm, 0.8--2.5 mm wide, linear to narrowly elliptic, rounded to obtuse at tip, flaccid. Staminate Inflorescence: bract 10--42 mm, proximally slender, distally 6--10 mm, 2.5--5 mm wide, elliptic, inflated, deciduous; peduncles, flowers deciduous soon after flowers open. Staminate Flower: sepals 3.5--5 mm, 2--2.5 mm wide, petals 4.5--5 mm. +- 0.5 mm wide. Pistillate Flower: sepals 1.4--2.8 mm, 1--1.3 mm wide; petals 1.8--4 mm, 1.1--1.3 mm wide. Seed: 2.8--3 mm, ellipsoid, dense-long-hairy.
Ecology: Shallow waters, streams; Elevation: 1300--1800 m. Bioregional Distribution: MP; Distribution Outside California: to British Columbia; western United States to Minnesota. Flowering Time: Jun--Aug
Synonyms: Elodea longivaginata H. St. John; Elodea nevadensis H. St. John
eFlora Treatment Author: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes
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Citation for this treatment: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes 2016. Elodea bifoliata, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=24049, accessed on September 29, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on September 29, 2016.


Geographic subdivisions for Elodea bifoliata:
MP;
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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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.