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Potamogeton pusillus
SMALL PONDWEED

Higher Taxonomy
Family: PotamogetonaceaeView DescriptionDichotomous Key

Common Name: PONDWEED FAMILY
Habit: Annual, perennial herb, aquatic, (generally fresh to alkaline), glabrous, from rhizomes, tubers, or winter buds. Stem: erect, simple to branched, cylindric to compressed, rooting at lower nodes; nodal glands present or not. Leaf: simple, cauline, alternate or in subopposite pairs; submersed thread-like to round, sessile or petioled; floating present or not, elliptic to ovate, petioled, leathery; sheath open, continuous with petiole or +- free from blade base, generally stipuled, stipules fused and ligule-like or not. Inflorescence: spike, cylindric to spheric, axillary or terminal, generally emergent, peduncled; bracts 0. Flower: inconspicuous, bisexual; perianth parts [0]4, clawed, +- green, limb generally adaxially concave; stamens [2]4, each fused to base of perianth part [or not], filament generally 0 [short, wide], anthers open to outside; pistils [1]4, ovary 1-chambered, ovule 1, attached to chamber base, style 0 or short. Fruit: drupe, generally obovate, sessile. Seed: 1.
Genera In Family: 3 genera, +- 95 species: worldwide. Note: Recently treated elsewhere to include Zannichelliaceae. Ruppia moved to Ruppiaceae.
eFlora Treatment Author: C. Barre Hellquist, Robert F. Thorne & Robert R. Haynes
Scientific Editor: Thomas J. Rosatti.
Genus: PotamogetonView DescriptionDichotomous Key

Common Name: PONDWEED
Habit: Annual, perennial herb, rhizomed or not, tubers 0, winter buds generally 0. Stem: simple or branched, cylindric to compressed; nodal glands present or 0. Leaf: submersed, also floating or not, generally flat, generally green, entire to finely serrate; submersed sessile or not, linear to round, tip rounded to acuminate, veins 1--35; floating 0 or generally petioled, elliptic to ovate, leathery; stipules of submersed leaves free from blade base or fused to it < 1/2 stipule length. Inflorescence: generally floating to emergent; peduncle stiff. Fruit: generally beaked, abaxially with 0 or 1 central keel, 0 or 2 lateral, sometimes lower keels, sides concave to convex.
Species In Genus: +- 88 species: generally temperate northern hemisphere. Etymology: (Greek: river neighbor, from aquatic habitat) Note: Other taxa in TJM (1993) moved to Stuckenia.

Potamogeton pusillus L.
NATIVE
Habit: Annual (perennial herb), rhizomes rare, slender, winter buds terminal or lateral. Stem: < 100 cm, cylindric; nodal glands present. Leaf: submersed, sessile, thread-like to linear, veins 1--3(7); stipules fused below middle. Inflorescence: +- interrupted, whorls 2--4; peduncles 0.5--8 cm. Fruit: < 2.5 mm, keels 0, sides concave, tip symmetric, beak at top.
Ecology: Shallow water, ponds, lakes, vernal pools, slow streams; Elevation: < 2700 m. Bioregional Distribution: NCo, KR, n SNF, SNH, GV, SnFrB, SCoR, SW (exc ChI), GB, DMoj; Distribution Outside California: circumboreal. Flowering Time: May--Jun
Synonyms: Potamogeton pusillus subsp. pusillus; Potamogeton pusillus var. pusillus
eFlora Treatment Author: C. Barre Hellquist, Robert F. Thorne & Robert R. Haynes
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Citation for this treatment: C. Barre Hellquist, Robert F. Thorne & Robert R. Haynes 2016. Potamogeton pusillus, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=39612, accessed on August 27, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on August 27, 2016.


Potamogeton pusillus
click for enlargement
© 2007 Neal Kramer
Potamogeton pusillus
click for enlargement
© 2007 Neal Kramer

More photos of Potamogeton pusillus in CalPhotos


Geographic subdivisions for Potamogeton pusillus:
NCo, KR, n SNF, SNH, GV, SnFrB, SCoR, SW (exc ChI), GB, DMoj;
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.