Common Names in English:
or rarely annual
or not rhizomatous, caulescent
; turions absent or present. Leaves alternate or nearly opposite, submersed
or both submersed and floating, sessile or petiolate
not persisting longer
, not leaving circular scar
when shed, ligulate
, not auriculate
, or rarely auriculate; intravaginal squamules
, more than 2. Inflorescences terminal
, spikes, capitate spikes, or panicles of spikes, not subtended by spathe
; peduncle not elongating, not spiraling following fertilization. Flowers bisexual
bracts absent; tepals 4 in 1 series; stamens [2 or] 4, epitepalous, in 1 series; anthers
, dehiscing vertically; pollen spheric; pistils 1 or 4, mostly not stipitate
, rarely short-stipitate; ovules marginal
. Fruits drupaceous
. Seeds 1; embryo curved
Genera 3, species ca. 90 (2 genera, 37 species in the flora ) : nearly worldwide.
The family has historically been considered to consist of two genera, Potamogeton and Groenlandia. Recent molecular evidence (D. H. Les, unpublished), combined with existing morphologic evidence, indicates that Potamogeton in the broad sense actually represents two separate lineages . We recognize those lineages at the generic level, Potamogeton in the strict sense and Stuckenia. Consequently, we accept three genera in the family, Potamogeton, Stuckenia, and Groenlandia.
Members of Potamogetonaceae have been variously combined with members of Zosteraceae, Cymodoceaceae, Zannichelliaceae, and Najadaceae to comprise compose Zosteraceae, Najadaceae, or Potamogetonaceae. Potamogetonaceae, as here interpreted, are separated from the other families by their bisexual flowers, the absence of spathelike bracts, and in some species, the presence of turions.
Aquatic vascular plants are known for their phenotypic plasticity (R. R. Haynes 1974) . Plasticity may result from the varied environmental conditions in which the populations grow or from morphologic changes in individuals of a population during the growing season (R. R. Haynes 1975) . Individuals in fruit have relatively consistent morphology within a species. Regardless of phenotypic plasticity, collections of Potamogetonaceae (and aquatic vascular plants in general) are often taken with little attention to the presence or absence of reproductive structures.
Reproductive features are most important in separating species of Potamogeton (R. R. Haynes 1978), and we include the entire family here. The keys may not always utilize reproductive features, but they are based on fruiting individuals. We strongly recommend that no one collect specimens of Potamogetonaceae that are lacking reproductive structures.
Leaves of Potamogetonaceae are stipulate . The stipules form a tubular sheath (stipular sheath) around the stem, free from or adnate to the base of the blade. In some species the leaf and sheath of submersed leaves are adnate for part of their length , and the leaf appears to have a sheathing base with an adaxial ligule at the junction of sheath and blade or petiole .
Fruits of Potamogetonaceae are drupaceous. The fruits do have endocarps but do not have fleshy mesocarps . Mesocarps exist but never become fleshy. Consequently, the fruits are not true drupes, they are drupaceous.
Many species of Potamogetonaceae undergo extensive vegetative reproduction either by turions or stem fragmentation. Turions are excellent modes of vegetative reproduction. The structures are produced at the stem tips and eventually fall to the substrate, either by a portion of the stem breaking off or by the stem itself falling to the substrate. The turions survive an unfavorable season , germinate , and grow into new plants during the next growing season. Because the unfavorable season is usually winter in North America, turions have been called "winter buds." At least one species, Potamogeton crispus, produces turions in early summer, and the turions survive the unfavorable season (summer, in this instance), germinating in the fall. The plant then survives the winter as a young individual, only a few centimeters long, even under ice, and begins growth as the water warms in the following spring . "Winter bud" is certainly not the correct term for P. crispus. The term "turions" designates all such structures, regardless of the unfavorable season.
Herbs: rhizomes present or absent; tubers absent; turions present or absent. Stems terete
, nodes occasionally with oil glands
; turions with extremely shortened internodes, divided
into outer and inner leaves; outer leaves 1--5 per side, similar to vegetative
leaves or occasionally corrugate near base
; inner leaves 1--10, rolled into fusiform
structure, unmodified, or shortened and oriented at 90° angles
to outer leaves. Leaves submersed
or both submersed and floating, alternate to nearly opposite; stipules connate
or not, if not, then convolute, tubular
stem and young inflorescences. Submersed leaves sessile or petiolate
; stipules either free
from or adnate
to base of leaf blade
for less than ½ length
of stipule, if adnate, then extending past adnation as free ligule; blade translucent, linear
to orbiculate, not channeled
, flattened, base acute to perfoliate, margins
entire or serrate, rarely crispate
, apex subulate
; veins 1--35. Floating leaves petiolate, rarely nearly sessile; stipules free from base of leaf blade; blade elliptic to ovate
, leathery, base cuneate to rounded
or cordate, margins entire, apex acute to obtuse; veins 1--51. Inflorescences spikes or panicles of spikes, submersed or emersed
, capitate or cylindric
; peduncles stiff, if long enough then projecting
inflorescence above surface of water. Flowers: pistils 1 or 4. Fruits abaxially rounded or keeled
, flattened to turgid
; embryo coiled
1 or more times. x
= 13 or 14.
Species ca. 100: nearly worldwide.
Potamogeton is one of the most important genera in the aquatic environment, especially as food or habitat for aquatic animals (R. R. Haynes 1975). A few species become slightly weedy, but not significantly so. Plants of Potamogeton are important in stabilizing substrates and removing particulate matter from the water column .
The genus has been divided into several sections and numerous subsections (predominantly by J. O. Hagström 1916; see also R. R. Haynes 1975, 1985 for in-depth coverage of three subsections). After studying thousands of specimens over at least five continents, we believe that recognition of the many infrageneric categories is unwarranted. Consequently, we are not including infrageneric classification here.
Hybridization is common among members of the genus (J. O. Hagström 1916). Numerous hybrids were proposed, using intermediate stem anatomy as evidence of hybrid origin . We list all the hybrids that Hagström proposed for species that occur in North America. An additional 26 hybrids have been recognized for the British Isles (C. D. Preston 1995).
Vegetative and reproductive morphology varies considerably in the genus. Two types of stems occur, rhizomes and erect stems. Some species have both, others have only erect stems. Two types of leaves exist, submersed and floating. Floating leaves have well-developed epidermis abaxially and adaxially, and well-developed cuticle at least adaxially. Floating leaves may be similar in shape to that of the submersed, or they may differ considerably. Submersed leaves have no cuticle and do not have well-developed epidermis. All species of Potamogeton have submersed leaves; some also have floating leaves. Occasionally, individuals of floating-leaved species lose their submersed leaves because of decay or wave action. Leaves of Potamogeton may be sessile or petiolate and are divided into at least blade and stipule. The stipule may be adnate to the blade for 1/3 or less the length of the stipule. Venation in the stipule is parallel, and veins may appear coarse as distinct ridges on the stipule (fibrous ), or they may be much less obvious, even difficult to observe (delicate). Stipular tissue between veins of fibrous stipules decays, leaving strands of fibers, whereas veins and the tissue between them decay in delicate stipules.
Many species have oil glands on the stem at the node of submersed leaves. These glands are especially common on species with sessile leaves. Circular and ranging from green to golden to white, they are present at most nodes, sometimes at all, or possibly only occasionally present. The glands (or nodal glands) are best observed with dried specimenses, a good light source, and magnification of at least 15´, although they can be observed under less ideal conditions.
Inflorescences may be either emergent or submersed. Emergent inflorescences are elongate and almost always terminal on the stem, whereas submersed inflorescences are globular and axillary . Most species have either emergent inflorescences or submersed inflorescences, but not both (monomorphic ). Other species have both types of inflorescences on one plant (dimorphic ).
All specimens should be collected when in fruit. Fruiting characteristics are extremely important in the genus, although they are not always given in the key . Vegetative features during fruiting are distinctive for the species; consequently, they are included in the key. Important features of the fruit include presence or absence of lateral and abaxial wings , ribs , ridges, or keels. Here, "ribbed" indicates a raised "vein" on a rounded surface; "ridged,"; a ridge with an obtuse angle; "keeled," a ridge with an acute angle; and "winged," a ridge that appears to have a wing distally.
Species Potamogeton hillii
Rhizomes absent. Cauline stems slightly compressed
, without spots,
30--60 cm; glands
rare, when present, brown to green, 0.1--0.3 mm
diam. Turions terminal
, rare, 2.8--3 cm ´ 1.5--3 mm, soft;
leaves ± 2-ranked; outer leaves 3--4 per side, base
apex acute to apiculate
; inner leaves undifferentiated. Leaves submersed
± spirally arranged
, sessile, delicate; stipules persistent
inconspicuous, convolute, free
, white to light brown,
, 0.7--1.6 cm, slightly fibrous
, rarely shredding
, apex obtuse
; blade pale green to olive-green, linear
, not arcuate
2--6 cm ´ 0.6--2.5(--4) mm, base slightly tapering, without
, not clasping
entire, not crispate
, apex not
hoodlike, apiculate to bristle-tipped or rarely blunt
, lacunae in
each side of midrib
; veins 3. Inflorescences unbranched,
; peduncles not dimorphic
and/or terminal, erect
, rarely recurved, slightly clavate
, 6--13.5 mm; spikes
not dimorphic, globose
, (2--) 4--7 mm.
Fruits brown to light greenish
, sessile, abaxially and laterally
(3-keeled), 2.3--4 ´ 2--3.2 mm, lateral keels
erect, 0.3--0.7 mm; sides without basal tubercles; embryo
with 1 full spiral
. Chromosome number unknownnot available. Flowering
and fruiting summer. [source]
Potamogeton hillii is an easily recognized species either in fruit or when sterile . The leaf blade has a bristle tip and five or fewer veins. Those characters combined with the usual absence of nodal glands will separate this species from all other North American linear-leaved species. Ecologically, it is consistently found in more alkaline waters than any other North American pondweed. A study of 35 localities established the mean to be 124.1 mg/l CaCO3 (C. B . Hellquist 1984). [source]
Flowers: Bloom Period: May, June, July.
Alkaline waters of marshes, ponds , lakes , and slow-moving streams ; 50--400 m .
- Whittaker & Margulis,1978
- Haeckel, 1866
- Cavalier-Smith, 1981
- Sinnott, 1935 ex Cavalier-Smith, 1998
- Vascular Plants
- Kenrick & Crane, 1997
- Brongniart, 1843
- Takhtajan, 1967
- Takhtajan, 1967
- Order: Alismatales () - Dumortier, 1829
- Superorder: Alismatanae () - Takhtajan, 1967
- Subclass: Alismatidae () - Takhtajan, 1967
- Class: Spermatopsida () - Brongniart, 1843
- Infraphylum: Radiatopses () - Kenrick & Crane, 1997
- Subphylum: Euphyllophytina ()
- Phylum: Tracheophyta () - Sinnott, 1935 ex Cavalier-Smith, 1998 - Vascular Plants
- Subkingdom: Viridaeplantae () - Cavalier-Smith, 1981
- Kingdom: Plantae () - Haeckel, 1866 - Plants
Potamogeton porteri Fernald
: Morong Publication
: Bot. Gaz. 6: 290 1881
Name Status: Accepted Name .
Last scrutiny: 15-Mar-2000
Members of the genus Potamogeton
ZipcodeZoo has pages for 91 species, subspecies, varieties, forms, and cultivars in this genus:
P. alpinus (Alpine Pondweed) · P. amplifolius (Large-Leaf Pondweed) · P. argutulus (Pondweed) · P. bicupulatus (Snailseed Pondweed) · P. bottnicus (Pondweed) · P. clystocarpus (Little Aguja Pondweed) · P. cognatus (Pondweed) · P. confervoides (Tuckerman's Pondweed) · P. crispus (Curled Pondweed) · P. cymatodes (Pondweed) · P. diversifolius (Waterthread) · P. epihydrus (Ribbonleaf Pondweed) · P. faxonii (Faxon's Pondweed) · P. floridanus (Florida Pondweed) · P. foliosus fibrillosus (Leafy Pondweed) · P. foliosus var. californicus (Leafy Pondweed) · P. foliosus subsp. fibrillosus (Leafy Pondweed) · P. friesii (Flat-Stalk Pondweed) · P. gessnacensis (Pondweed) · P. gramineus (Grass-Leaved Pondweed) · P. gramineus var. spathulaeformis (Various-Leaf Pondweed) · P. griffithii (Griffith's Pondweed) · P. groenlandicus (Greenland Pondweed) · P. hagstroemii (Hagstroem's Pondweed) · P. haynesii (Haynes' Pondweed) · P. hillii (Hill's Pondweed) · P. illinoensis (Illinois Pondweed) · P. insulanus (Tropical Pondweed) · P. kochii (Koch's Pondweed) · P. lucens (Shining Pondweed) · P. marianensis (Pondweed) · P. methyensis (Methy Lake Pondweed) · P. mysticus (Mystic Pondweed) · P. natans (Broad-Leaved Pondweed) · P. nericus (Pondweed) · P. nitens (Pondweed) · P. nodosus (Long-Leaf Pondweed) · P. oakesianus (Oakes' Pondweed) · P. oblongus (Cinnamonspot Pondweed) · P. obtusifolius (Blunt-Leaved Pondweed) · P. ochreatus (Blunt Pondweed) · P. ogdenii (Ogden's Pondweed) · P. perfoliatus (Claspingleaf Pondweed) · P. perfoliatus perfoliatus (Claspingleaf Pondweed) · P. perfoliatus var. lanceolatus (Hiroha-No-Ebi-Mo) · P. praelongus (White-Stem Pondweed) · P. prussicus (Pondweed) · P. pulcher (Heartleaf Pondweed) · P. pusilliformis (Pondweed) · P. pusillus (Lesser Pondweed) · P. pusillus var. polyphyllus (Small Pondweed) · P. pusillus var. tenuifolius (Small Pondweed) · P. pusillus subsp. gemmiparus (Small Pondweed) · P. pusillus subsp. tenuissimus (Small Pondweed) · P. rectifolius (Pondweed) · P. richardsonii (Red-Head Pondweed) · P. robbinsii (Robbins Pondweed) · P. saxonicus (Pondweed) · P. schreberi (Schreber's Pondweed) · P. scoliophyllus (Pondweed) · P. semenii (Semen's Pondweed) · P. semifructus (Pondweed) · P. sparganiifolius (Pondweed) · P. spathuliformis (Pondweed) · P. spirillus (Spiral Pondweed) · P. strictifolius (Narrowleaf Pondweed) · P. subobtusus (Pondweed) · P. subsessilis (Pondweed) · P. subsibiricus (Yenisei River Pondweed) · P. suecicus (Pondweed) · P. tennesseensis (Tennessee Pondweed) · P. tricarinatus (Floating Pondweed) · P. trichoides (Hairlike Pondweed) · P. undulatus (Pondweed) · P. vaseyi (Vasey's Pondweed) · P. vilnensis (Pondweed) · P. x bottnicus (Pondweed) · P. × cognatus (Pondweed) · P. x gessnacensis (Pondweed) · P. x griffithii (Griffith's Pondweed) · P. × haynesii (Haynes' Pondweed) · P. x mysticus (Mystic Pondweed) · P. x nitens (Pondweed) · P. x prussicus (Pondweed) · P. × pusilliformis (Pondweed) · P. x schreberi (Schreber's Pondweed) · P. × scoliophyllus (Pondweed) · P. x sparganiifolius (Pondweed) · P. × subsessilis (Pondweed) · P. × undulatus (Pondweed) · P. zosteriformis (Flat-Stem Pondweed)
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- Catalog of Ohio vascular plants: arranged according to the phyletic classification: with notes on the geographical distribution in the state, based mainly on specimens in the State Herbarium, Botanical Laboratory, the Ohio State Uni by John H. Schaffner. Columbus: Ohio State University, 1914. url p. 137.
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- Preston, C. D. 1995. Pondweeds of Great Britain and Ireland. Botanical Society of the British Isles, London. Handbook No. 8.
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- Global Biodiversity Information Facility. Accessed November 21, 2007. http://www.gbif.org Mediated distribution data from 4 providers.
- "Potamogeton hillii". in Flora of North America Vol. 22. Published by Oxford University Press. Online at EFloras.org.
- Ruggiero M., Gordon D., Bailly N., Kirk P., Nicolson D. (2011). The Catalogue of Life Taxonomic Classification, Edition 2, Part A. In: Species 2000 & ITIS Catalogue of Life: 2011 Annual Checklist (Bisby F.A., Roskov Y.R., Orrell T.M., Nicolson D., Paglinawan L.E., Bailly N., Kirk P.M., Bourgoin T., Baillargeon G., Ouvrard D., eds). DVD; Species 2000: Reading, UK.
- The International Plant Names Index. Accessed Dec 27, 2011.
Accessed through GBIF Data Portal November 21, 2007:
- Canadian Museum of Nature, Canadian Museum of Nature Herbarium
- USDA PLANTS, USDA PLANTS Database
- University of Alabama Biodiversity and Systematics, Herbarium
- Biodiversity Heritage Library NamebankID: 2659767
- Catalogue of Life Accepted Name Code: ITS-39034
- Global Biodiversity Information Facility Taxonkey: 13751066
- Globally Unique Identifier: urn:lsid:ipni.org:names:603249-1
- Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 39034
- International Plant Names Index (IPNI) ID: 603249-1
- U.S.D.A. Plant Symbol: POPO14
- Zipcode Zoo Species Identifier: 57093
- Robert R. Haynes ,C. Barre Hellquist "Potamogetonaceae". in Flora of North America Vol. 22. Oxford University Press. Online at EFloras.org. [back]
- "Potamogeton". in Flora of North America Vol. 22. Oxford University Press. Online at EFloras.org. [back]
- "Potamogeton hillii". in Flora of North America Vol. 22. Oxford University Press. Online at EFloras.org. [back]