font settings and languages

Font Size: Large | Normal | Small
Font Face: Verdana | Geneva | Georgia
Languages:

Potamogeton nodosus

(Long-Leaf Pondweed)

Common Names

[ Back to top ]

Click on the language to view common names.

Common Names in English:

Long-Leaf Pondweed, Longleaf Pondweed

Common Names in French:

Potamot Noeuex

Description

[ Back to top ]

Family Potamogetonaceae

Herbs, perennial or rarely annual , rhizomatous or not rhizomatous, caulescent ; turions absent or present. Leaves alternate or nearly opposite, submersed or both submersed and floating, sessile or petiolate ; sheath not persisting longer than blade , not leaving circular scar when shed, ligulate , not auriculate , or rarely auriculate; intravaginal squamules scales , more than 2. Inflorescences terminal or axillary , spikes, capitate spikes, or panicles of spikes, not subtended by spathe , pedunculate ; peduncle not elongating, not spiraling following fertilization. Flowers bisexual ; subtending bracts absent; tepals 4 in 1 series; stamens [2 or] 4, epitepalous, in 1 series; anthers distinct , dehiscing vertically; pollen spheric; pistils 1 or 4, mostly not stipitate , rarely short-stipitate; ovules marginal , orthotropous . 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 Recent molecular evidence (D. H. Les, unpublished), combined with existing morphologic evidence, indicates that Potamogeton in the broad sense actually represents two separate lineages .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.[1]

Genus Potamogeton

Herbs: rhizomes present or absent; tubers absent; turions present or absent. Stems terete or compressed , 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 , sheathing 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 to obtuse ; 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 , beaked ; 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&#180, 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.[2]

Physical Description

Species Potamogeton nodosus

Rhizomes present. Cauline stems terete , without spots, to 100 cm; nodal glands absent. Turions absent. Leaves both submersed and floating, or floating absent, ± spirally arranged . Submersed leaves petiolate , lax ; stipules persistent to deliquescent, conspicuous , convolute, free from blade , light brown, not ligulate , 3--9 cm, not fibrous , not shredding at tip , apex round to acute; petioles 2--13 cm; blade light to dark green, linear-lanceolate to lance-elliptic, not arcuate , 9--20 cm ´ 10--35 mm, base acute, without basal lobes , not clasping , margins entire, not crispate , apex not hoodlike, acute, without sharp awl-like tip, lacunae in 2--5 rows each side of midrib ; veins 7--15. Floating leaves: petioles 3.5--26 cm; blade adaxially light green, lenticular to elliptic , 3--11 cm ´ 15--45 mm, base cuneate to rounded , apex acute to rounded; veins 9--21. Inflorescences unbranched, emersed ; peduncles not dimorphic , terminal , erect to ascending , cylindric , 3--15 cm; spikes not dimorphic, cylindric, 20--70 mm. Fruits sessile, red to reddish brown, obovoid , abaxially keeled , laterally ridged , 2.7--4.3 ´ 2.5--3 mm, keel well developed, lateral ridges with blunt to sharp tips; beak erect; sides without basal tubercles; embryo with 1 full spiral . 2n = 52. [source]

Six hybrids, Potamogeton gramineus ´ P. nodosus (= P. ´ argutulus Hagström), P. illinoensis ´ P. nodosus (= P. ´ faxonii Morong), P. nodosus ´ P. richardsonii (= P. ´ rectifolius A. Bennett), P. natans ´ P. nodosus (= P. ´ schreberi Fischer [P. ´ perplexus A. Bennett]), P. alpinus ´ P. nodosus (= P. ´ subotusus Hagström), and P. epihydrus ´ P. nodosus (= P. ´ subsessilis Hagström), have been described. [source]

Potamogeton nodosus is a common floating-leaved species throughout much of the United States and southern Canada. When both submersed and floating leaves are present, it is very easily recognized by the petioles of the submersed leaves being longer than 5 cm. [source]

Habit: Forb/herb

Flowers: Bloom Period: May, June, July, August, September, October.

Habitat

Clear to turbid waters of lakes , streams , rivers , and sloughs ; 0--3300 m [3].

Typically found at an altitude of 0 to 3,180 meters (0 to 10,433 feet).[4]

Biology

[ Back to top ]

Reproduction

Duration: Perennial

Taxonomy

[ Back to top ]

Unambiguous Synonyms

  1. Potamogeton americanus Cham. & Schlecht.
  2. Potamogeton fluitans Roth

Notes

Publishing author : Roth Publishing author: Roem. & Schult. Publication : Syst. iii. 509 Name Status: Accepted Name . Latest taxonomic scrutiny: 15-Mar-2000

Place of publication: Encycl. suppl. 4:535. 1816

Name verified on 28-Apr-2000 by ARS Systematic Botanists. Last updated: 10-Mar-2003

Similar Species

[ Back to top ]

Members of the genus Potamogeton

ZipcodeZoo has pages for 535 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:

P. acuminatus · P. acutifolius · P. affinis · P. alatus · P. alpino-natans · P. alpinus (Alpine Pondweed) · P. alpinus tenuifolius · P. amblyophyllus · P. americanus · P. americanus var. novaeboracensis · P. amplexicaulis · P. amplifolius (Broad-Leaved Pondweed) · P. amplifolius var. ovalifolius · P. anadyrensis · P. anglicus · P. anguillanus · P. angustifolium · P. angustifolius · P. angustifolius var. connecticutensis · P. angustissimus · P. annulatus · P. antaicus · P. apertus · P. apicalis · P. applanatus · P. argutulus (Pondweed) · P. aschersonii · P. asiaticus · P. attenuatus · P. augustanus · P. aulacophyllus · P. australiensis · P. australis · P. austriacus · P. austrosibiricus · P. badiovirens · P. baenitzii · P. balatonicus · P. bambergensis · P. bennettii · P. berchtoldi · P. berchtoldii · P. berchtoldii subsp. tenuissimus · P. berteroanus · P. bicupulatus (Snail-Seed Pondweed) · P. bifolius · P. biformis · P. billotii · P. billupsii · P. biwaensis · P. borealis · P. bottnicus (Pondweed) · P. bracteatus · P. brasiliensis · P. bupleuroides · P. burkartii · P. californicus · P. canariensis · P. capensis · P. capillaceus · P. capricorni · P. caricifolius · P. carinatus · P. casparyi · P. cayugensis · P. cespitosus · P. chakassiensis · P. champlainii · P. cheesemanii · P. cheesemannii · P. chesemanii · P. chongyangensis · P. claytonii · P. clystocarpus (Little Aguja Pondweed) · P. cognatus (Pondweed) · P. coloratus · P. coloratus subsp. subflavus · P. coloratus var. jamaicensis · P. columbianus · P. complanatus · P. compressum · P. compressus · P. concilius · P. concinnitus · P. condylocarpus · P. confervoides (Tuckerman's Pondweed) · P. confinis · P. conjungens · P. contortus · P. cooperi · P. coriaceus · P. cornutus · P. crassipes · P. crenulatus · P. crispatus · P. crispus (Curly-Leaved Pondweed) · P. cristatus · P. cuspidatus · P. cymatodes (Pondweed) · P. danicus

More Info

[ Back to top ]

Further Reading

[ Back to top ]

Notes

[ Back to top ]

Contributors

Data Sources

Accessed through GBIF Data Portal November 22, 2007:

Identifiers

Footnotes

  1. Robert R. Haynes ,C. Barre Hellquist "Potamogetonaceae". in Flora of North America Vol. 22. Oxford University Press. Online at EFloras.org. [back]
  2. "Potamogeton". in Flora of North America Vol. 22. Oxford University Press. Online at EFloras.org. [back]
  3. "Potamogeton nodosus". in Flora of North America Vol. 22. Oxford University Press. Online at EFloras.org. [back]
  4. Mean = 251.570 meters (825.361 feet), Standard Deviation = 298.210 based on 5,440 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/1/2009