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Potamogeton illinoensis
SHINING 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 illinoensis Morong
NATIVE
Habit: Perennial herb, rhizomed. Stem: < 150 cm, branches generally many, slender, cylindric. Leaf: submersed blade 6--20 cm, 15--50 mm wide, elliptic to oblanceolate, microscopically serrate near tip, tip acute-mucronate, veins 7--19, petiole 0 or 0.5--4 cm; floating 0 or blade generally > petiole, 4--12 cm, 2--6 cm wide, widely elliptic to oblong-elliptic, tip rounded-mucronate, veins 13--29; stipules 2.5--7 cm, free, persistent. Inflorescence: generally < 6 cm. Fruit: 2.5--3.6 mm, keels 3, lateral lower, beak erect to +- recurved, 0.5--0.8 mm. Chromosomes: n=52.
Ecology: Lakes, ponds, streams; Elevation: 400--2350 m. Bioregional Distribution: NCoR, CaR, SNH, GV, CW (exc SCoRI), SnGb, SnBr, PR, GB; Distribution Outside California: to British Columbia, eastern Canada, Texas, Baja California; also Central America, South America, Caribbean. Flowering Time: Jun--Aug Note: Hybridizes with Potamogeton amplifolius, Potamogeton gramineus, Potamogeton nodosus, Potamogeton richardsonii.
eFlora Treatment Author: C. Barre Hellquist, Robert F. Thorne & Robert R. Haynes
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Previous taxon: Potamogeton gramineus
Next taxon: Potamogeton natans

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Citation for this treatment: C. Barre Hellquist, Robert F. Thorne & Robert R. Haynes 2016. Potamogeton illinoensis, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=39581, accessed on May 03, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on May 03, 2016.


Potamogeton illinoensis
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© 2008 Neal Kramer

More photos of Potamogeton illinoensis in CalPhotos


Geographic subdivisions for Potamogeton illinoensis:
NCoR, CaR, SNH, GV, CW (exc SCoRI), SnGb, SnBr, PR, 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.
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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.