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C. Barre Hellquist, Robert F. Thorne & Robert R. Haynes

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.
3 genera, ± 95 species: worldwide. [Haynes & Hellquist 2000 FNANM 22:47–74] Recently treated elsewhere to include Zannichelliaceae. Ruppia moved to Ruppiaceae. —Scientific Editor: Thomas J. Rosatti.
Unabridged references: [Angiosperm Phylogeny Group 1998 Ann Missouri Bot Gard 85:531–553]

Key to Potamogetonaceae

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.
± 88 species: generally temperate northern hemisphere. (Greek: river neighbor, from aquatic habitat) Other taxa in TJM (1993) moved to Stuckenia.
Unabridged references: [Haynes 1974 Rhodora 76:564–649; Haynes 1985 Sida 11:173–188; Wiegleb 1988 Fedde Rep Sp Nov Regni Veg 99:249–266; Wiegleb & Kaplan 1998, Folia Geobot 33: 241–316.]

Key to Potamogeton

P. amplifolius Tuck. BROAD-LEAVED PONDWEED
Perennial herb, rhizome stout. Stem: < 90 cm, branches 0 or above, cylindric. Leaf: often red-brown; submersed 8–20 cm, 2–7 cm wide, generally lanceolate to ovate, generally folded along midvein, curved backward, acute at both ends, veins 19–50; floating 5–10 cm, 2.5–5 cm wide, elliptic to ovate, tapered or rounded at both ends, veins 27–50; stipules generally 3–10 cm, free, fibrous in age, stringy. Inflorescence: generally < 5 cm. Fruit: 3–5 mm, keels 1 or 3, lateral 0 or lower, sides flat.
n=26. Uncommon. Deep, clear-water lakes; 600–1850 m. North Coast Ranges, High Cascade Range, High Sierra Nevada, Warner Mountains; to British Columbia, eastern North America. Hybridizes with Potamogeton illinoensis, Potamogeton praelongus, Potamogeton richardsonii. Jul–Aug [Online Interchange]

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Next taxon: Potamogeton berchtoldii


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Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora,, accessed on Nov 29 2015
Citation for this treatment: [Author of taxon treatment] 2013. Potamogeton, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on Nov 29 2015

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Geographic subdivisions indicated for the distribution of Potamogeton amplifolius 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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CCH collections by month

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