EICHHORNIA

EICHHORNIA CRASSIPES (Martius) Solms-Laub - Water-hyacinth. 2n = 30, 32, 58.

Floating in ponds and quiet streams. From South America.

HETERANTHERA

Heteranthera dubia (Jacquin) MacMillan - Water Stargrass. 2n = 30.

Shallow, quiet, basic water. [Zosterella dubia (Jacquin) Small]

Heteranthera reniformis Ruiz & Pavón - . 2n = 48.

Muddy river shores (in mud or floating in shallow water).

PONTEDERIA

Pontederia cordata Linnaeus - Pickerelweed. 2n = 16.

Shallow water of ponds, lakes and river shores, rooting in mud.

POTAMOGETON

Potamogeton alpinus Balbis - Red Pondweed. 2n = 26, 52.

Slow-moving streams, shallow water of ponds and lakes. [P. alpinus var. subellipticus (Fernald) Ogden;  P. alpinus var. tenuifolius (Rafinesque) Ogden]

Potamogeton amplifolius Tuckerman - . 2n = 52.

Deep water of lakes and river coves.

Potamogeton bicupulatus Fernald - . 2n = ?.

Acidic, shallow water of rivers and ponds. [P. diversifolius Rafinesque var. trichophyllus Morong;  P. capillaceus Poiret]

Potamogeton confervoides Reichenbach - Alga Pondweed. 2n = ?.

Acid sandy or sphagnous ponds, mountain pools and lakes.

POTAMOGETON CRISPUS Linnaeus - Curly Pondweed. 2n = 26, 36, 42, 50, 52, 72, 78.

Shallow, basic or brackish water. From Europe.

Potamogeton diversifolius Rafinesque - Common Snailseed Pondweed. 2n = ?.

Acidic shallow water. [P. capillaceus Poiret]

Potamogeton epihydrus Rafinesque - Ribbonleaf Pondweed. 2n = 26.

Shallow, quiet or moving water. [P. epihydrus var. nuttallii (Chamisso & Schlechtendahl) Fernald;  P. epihydrus var. ramosus (Peck) House]

Potamogeton foliosus Rafinesque subsp. foliosus - Leafy Pondweed. 2n = 26, 28.

Still, basic water of ponds, lakes and streams. [P. foliosus var. macellus Fernald]

Potamogeton friesii Ruprecht - . 2n = 26.

Alkaline, deep water of lakes and ponds.

Potamogeton gramineus Linnaeus - . 2n = 52.

Shallow water. [P. gramineus var. maximus Morong; P. gramineus var. myriophyllus Robbins]

Potamogeton hillii Morong - . 2n = 26.

Alkaline water of ponds and streams.

Potamogeton illinoensis Morong - . 2n = 104.

Alkaline water of ponds and streams.

Potamogeton natans Linnaeus - Floating Pondweed. 2n = 42, 52.

Ponds and slow streams.

Potamogeton nodosus Poiret - Longleaf Pondweed. 2n = 52.

Streams.

Potamogeton oakesianus Robbins - Oakes Pondweed. 2n = ?.

Acidic ponds and lakes.

Potamogeton obtusifolius Mertens & Koch - . 2n = 26.

Quiet, usually cold, basic water.

Potamogeton ogdenii Hellquist & R. L. Hilton - Ogden's Pondweed. 2n = ?.

Basic water of ponds and lakes.

Potamogeton perfoliatus Linnaeus - Redhead-grass. 2n = 14, ca. 40, 52, 78.

Shallow water. [P. perfoliatus var. bupleuroides (Fernald) Farwell]

Potamogeton praelongus Wulfen - White-stem Pondweed. 2n = 52.

Moderately alkaline, still, usually deep water.

Potamogeton pulcher Tuckerman - Spotted Pondweed. 2n = ?.

Acidic, shallow water of ponds and muddy shores.

Potamogeton pusillus Linnaeus subsp. pusillus - . 2n = 26.

Alkaline water of ponds and streams. [P. pusillus var. minor (Bivona-Bivardi) Fernald & B. G. Schubert]

Potamogeton pusillus Linnaeus subsp. gemmiparus (Robbins) R. R. Haynes & Hellquist - . 2n = 26.

Quiet, acidic water of ponds and streams. [P. gemmiparus (Robbins) Robbins ex Morong]

Potamogeton pusillus Linnaeus subsp. tenuissimus (Mertens & Koch) R. R. Haynes & Hellquist - . 2n = 26.

Quiet, shallow water of ponds and streams. [P. berchtoldii Fieber;  P. berchtoldii Fieber var. acuminatus Fieber;  P. berchtoldii Fieber var. lacunatus (Hagström) Fernald;  P. berchtoldii Fieber var. polyphyllus (Morong) Fernald;  P. berchtoldii Fieber var. tenuissimus (Mertens & Koch) Fernald]

Potamogeton richardsonii (A. Bennett) Rydberg - Redhead Pondweed. 2n = 26, 52.

Alkaline water of lakes and streams.

Potamogeton robbinsii Oakes - Fern Pondweed. 2n = 52.

Ponds, lakes and slow streams.

Potamogeton spirillus Tuckerman - Northern Snailseed Pondweed. 2n = ?.

Neutral to acidic, quiet water of ponds and streams.

Potamogeton strictifolius A. Bennett - . 2n = 52.

Alkaline water of lakes and slow streams. [P. strictifolius var. rutiloides Fernald]

Potamogeton vaseyi Robbins - Vasey's Pondweed. 2n = 28.

Quiet water of ponds and streams of low to moderate alkalinity. [P. lateralis Morong]

Potamogeton zosteriformis Fernald - Flatstem Pondweed. 2n = 52.

Quiet, often alkaline water of ponds and slow streams.

POTAMOGETON hybrids

Potamogeton alpinus Balbis X Potamogeton epihydrus Rafinesque - .

Potamogeton amplifolius Tuckerman X Potamogeton gramineus Linnaeus - .

Potamogeton amplifolius Tuckerman X Potamogeton illinoensis Morong - .

Potamogeton amplifolius Tuckerman X Potamogeton praelongus Wulfen - .

Potamogeton x argutulus Hagström - .

[P. gramineus Linnaeus X P. nodosus Poiret]

Potamogeton x faxonii Morong - .

[P. illinoensis Morong X P. nodosus Poiret]

Potamogeton x haynesii Hellquist & G. E. Crow - .

[P. strictifolius A. Bennett X P. zosteriformis Fernald; P. longiligulatus misapplied]

Potamogeton illinoensis Morong X Potamogeton perfoliatus Linnaeus - .

Potamogeton illinoensis Morong X Potamogeton richardsonii (A. Bennett) Rydberg - .

Potamogeton x mysticus Morong - .

[P. perfoliatus Linnaeus X P. pusillus Linnaeus subsp. tenuissimus (Mertens & Koch) R. R. Haynes & Hellquist]

Potamogeton x nericius Hagström - .

[P. alpinus Balbis X P. gramineus Linnaeus]

Potamogeton x nitens G. Weber - .

[P. gramineus Linnaeus X P. perfoliatus Linnaeus]

Potamogeton perfoliatus Linnaeus X Potamogeton richardsonii (A. Bennett) Rydberg - .

Potamogeton praelongus Wulfen X Potamogeton richardsonii (A. Bennett) Rydberg - .

Potamogeton x prussicus Hagström - .

[P. alpinus Balbis X P. perfoliatus Linnaeus]

Potamogeton x spathuliformis (Robbins) - .

[P. gramineus Linnaeus X P. illinoensis Morong]

STUCKENIA

Stuckenia filiformis (Persoon) Börner subsp. alpina (Blytt) R.R. Haynes, Les & M. Král - . 2n = 78.

Highly alkaline water of cold springs and lakes. [Potamogeton filiformis Persoon var. borealis (Rafinesque) St. John;  Potamogeton filiformis Persoon var. macounii Morong]

Stuckenia filiformis (Persoon) Börner subsp. occidentalis (J. W. Robbins) R.R. Haynes, Les & M. Král - . 2n = ?.

Highly alkaline water of cold streams.

Stuckenia pectinata (Linnaeus) Börner - Sago. 2n = 42, ca. 66, 70-87.

Brackish or alkaline waters. [Potamogeton pectinatus Linnaeus]

RUPPIA

Ruppia maritima Linnaeus - . 2n = 14, 16, 20, 24, 28, 40.

Saline or brackish water. [R. maritima var. longipes Hagström; R. maritima var. obliqua (Schur) Ascherson & Graebner; R. maritima var. rostrata Agardh; R. maritima var. subcapitata Fernald & Wiegand]

SCHEUCHZERIA

Scheuchzeria palustris Linnaeus - . 2n = 22.

Sphagnum bogs. [S. palustris var. americana Fernald]

SMILAX

Smilax glauca Walter - Sawbrier. 2n = 32.

Sandy thickets, open woods. [S. glauca Walter var. leurophylla Blake]

Smilax herbacea Linnaeus - Carrion-flower. 2n = 26.

Rich thickets, low woods.

Smilax pulverulenta Michaux - . 2n = ?.

Rich, mostly basic, woods and thickets. [S. herbacea Walter var. pulverulenta (Michaux) A. Gray]

Smilax rotundifolia Linnaeus - Common Greenbrier. 2n = 32.

Woods and thickets.

Smilax tamnoides Linnaeus - China-root. 2n = 32.

Low woods and thickets. [S. tamnoides var. hispida (Muhlenberg) Fernald; S. hispida Muhlenberg ex Torrey]

SPARGANIUM

Sparganium americanum Nuttall - . 2n = ?.

Muddy shores, shallow water.

Sparganium androcladum (Engelmann) Morong - . 2n = ?.

Muddy shores, marshes, shallow water.

Sparganium angustifolium Michaux - . 2n = 30.

Shallow or deep water, shores. [S. multipedunculatum (Morong) Rydberg]

Sparganium emersum Rehmann - . 2n = 30.

Muddy shores, marshes, shallow water [S. chlorocarpum Rydberg; S. chlorocarpum Rydberg var. acaule (Beeby) Fernald]

Sparganium eurycarpum Engelmann - . 2n = 30.

Mostly basic, muddy shores, marshes, shallow water.

Sparganium fluctuans (Engelmann ex Morong) B. L. Robinson - . 2n = ?.

Non-basic lakes and ponds.

Sparganium natans Linnaeus - . 2n = 30.

Shallow pools, streams, shores, bogs. [S. minimum (Hartman) Fries]

SPARGANIUM hybrids

Sparganium americanum Nuttall X Sparganium fluctuans (Engelmann ex Morong) B. L. Robinson - .

Sparganium angustifolium Michaux X Sparganium emersum Rehmann - .

TYPHA

Typha angustifolia Linnaeus - . 2n = 30.

Salt marshes, inland marshes, mostly alkaline or near highways.

Typha latifolia Linnaeus - Common Cat-tail. 2n = 30.

Marshes, shores, roadside ditches.

TYPHA hybrid

Typha x glauca Godron - .

[T. angustifolia Linnaeus X T. latifolia Linnaeus]

XYRIS

Xyris difformis Chapman var. difformis - Common Yellow-eyed Grass. 2n = 18.

Sandy shores of acid ponds, lakes and bogs. [X. caroliniana misapplied]

Xyris montana Ries - Small Yellow-eyed Grass. 2n = ?.

Sandy, mostly acidic shores and bogs.

Xyris smalliana Nash - . 2n = 18.

Muddy shores, bogs, swamps, sandy or sphagnous shallows. [X. caroliniana Walter;  X. congdoni Small]

Xyris torta Smith - . 2n = 18.

Sandy shores, sphagnous depressions, meadows.

ZANNICHELLIA

Zannichellia palustris Linnaeus - Horned Pondweed. 2n = 12, 24, 28, 32, 34, 36, 48.

Fresh to brackish water of lakes, streams and estuaries. [Z. palustris var. major (Hartman) W. D. J. Koch]

ZOSTERA

Zostera marina Linnaeus - Common Eel-grass. 2n = 12.

Shallow waters of coastal estuaries, coves, and bays. [Z. marina var. stenophylla Ascherson & Graebner]