Common Aquatic Weeds & Algae of Canada and U.S.A.

Common Aquatic Weeds & Algaeof Canada and U.S.A. Basic Identification and Information Guide Revision Date: June 20, 2019 START MENU

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(1) (1) Click on the picture that most closely resembles the algae you wish to identify (10) Filamentous or Planktonic Chara spp. Nitella spp. Algae can be generally categorized by the form it takes in water (ex. planktonic, filamentous, erect), or by algal groups (ex. green algae, blue-green algae etc.) Back to Menu

Planktonic algae are floating microscope plants that are normal and essential inhabitants of sunlit surface waters. There are literally millions of floating planktonic algae that turn pond water shades of green, blue-green, brown or variations in between. Planktonic algae that colors the water is often called a “bloom” or “algae bloom”. Many species of planktonic algae can be present at the same time in a water body1. Filamentous algae are single algae cells that form long visible chains, threads, or filaments. These filaments intertwine forming a mat that resembles wet wool. Filamentous algae starts growing along the bottom in shallow water or attached to structures in the water (like rocks or other aquatic plants). Often filamentous algae floats to the surface forming large mats, which are commonly referred to as “pond scums”. There are many species of filamentous algae and often more than one species will be present at the same time1. Planktonic and Filamentous Algae Some common types of planktonic algae include: Chlamydomonas, Chlorella, Euglena,Closterium, Anacystis spp., etc. Some common types of filamentous algae include: Spirogyra, Anabaena, Oscillatoria, Lyngbya, Pithophora spp., etc (1) (1) Back to Algae Menu NEXT ALGAE PAGE

Different Algae Groups Green Algae:a very large and diverse group of algae (mostly freshwater). Typically green, but not always. During a bloom, water generally looks greenish in colour. Some are motile, while others are sessile. Some common Green Algae are shown below6: Blue-Green Algae (Cyanobacteria):Used to be considered algae, but is actually more closely related to bacteria. A cyanobacteria bloom is obvious when the water turns a blue-green colour. Some common Cyanobacteria are shown below6: Planktonic forms Filamentous forms Back to Algae Menu BACK NEXT ALGAE PAGE

Different Algae Groups Diatoms:Usually yellow-brown in colour, with rigid looking cell walls. Diatoms are usually sessile and can be numerous in fresh water. Some common diatoms are shown below6: Red Algae:Not very common in fresh water, and not always red. Most Red Algae is marine. Often during a bloom, water will appear brown or reddish. Some common Red Algae are shown below6: BACK Back to Algae Menu NEXT ALGAE PAGE

Desmids:Fairly common freshwater algae. Many have 2 semi cells that are mirror images. Some of the very large desmids can be seen without magnification. Some common desmids are shown below6: Different Algae Groups Please click on the link below, then click on ALGAE on the webpage for further algae information Pond Identification BACK Back to Algae Menu

Chara spp. • Chara is often called muskgrass or skunkweed because of its foul, musty almost garlic-like odor. Chara is a gray-green branched multicellular algae that is often confused with submerged flowering plants. However, Chara has no flower, will not extend above the water surface, and often has a “grainy” or “crunchy” texture. Chara has cylindrical, whorled branches with 6 to 16 branchlets around each node1. (1) Distribution: Worldwide (10) Back to Algae Menu

Nitella spp. • A special kind of algae that grows only in fresh water is Nitella (also known as stoneworts). They resemble small tress and grow in miniature forests at the lake bottom; they are known for their unpleasant smell. Nitella is branched multicellular algae that is often confused with submerged flowering plants. However, it has no flower and will not extend above the water surface. Nitella has no odor and is soft to the touch, unlike Chara. Stoneworts are light to dark green in color with forked, bushy branches 1/16 to 1/8 inches in diameter1. (1) Distribution: Worldwide (1) Back to Algae Menu

(9) Aquatic Plants Click on the category of aquatic plant that you wish to identify Floating Submersed Emergent Back to Menu

Floating Aquatic Plants Clickon a picture to select a plant Duckweed Watermeal Watershield Water Hyacinth White Water Lily Yellow Water Lily Back to Aquatic Plant Menu

(4) (1) Duckweed – Lemna spp., Spirodela spp. • Common Duckweed is a very small light green free-floating, seed bearing plant. Duckweed has 1 to 3 leaves - 1/16 – 1/8 inch in length. A single root hair protrudes from each tiny leaf. Giant or big duckweed is still relatively small 1/16 to 1/4 inch with 1 to 4 leaves with three or more roots hairs protruding from each leaf. Duckweeds tend to grow in dense colonies in undisturbed waters or ponds, and can be aggressive invaders of ponds. These plants should be controlled before they cover the entire surface of the pond1. Distribution: Worldwide Back to Floating Plant Menu

(1) Watermeal - Wolfia spp. • Watermeal is a very tiny (<1mm) light green free-floating, rootless plant. Watermeal tends to grow in dense colonies in undisturbed water. Often watermeal will be associated with colonies of duckweeds. Watermeal can be an aggressive invader of ponds and are often found mixed in with duckweeds and other aquatic plants. If colonies cover the surface of the water, then oxygen depletions and fish kills can occur. These plants should be controlled before they cover the entire surface of the pond1. Distribution: Worldwide Back to Floating Plant Menu

(4) (4) Watershield - Brasenia spp. • Watershield is an aquatic floating perennial. Leaves are alternate, floating, oval to elliptic in outline, and approximately 4 1/2 inches long and 2 1/2 inches wide. Leaves are green and shiny on the upper surface and purple on the lower surface. The undersides of the leaves are covered with a thick, jelly-like substance. The leaves occur on petioles that range from 4 to 12 inches in length. Stems are branched and may reach 6 feet in length. Primarily a weed of poorly-managed lakes or ponds that most commonly occurs in water up to about 5 feet deep4. Distribution: Throughout most of US to Southern Canada Back to Floating Plant Menu

(1) (1) Water Hyacinth – Eichhoria crassipes • Water Hyacinth is a free-floating perennial plant that can grow to a height of 3 feet. The dark green leave blades are circular to elliptical in shape attached to a spongy, inflated petiole. Underneath the water is a thick, heavily branched, dark fibrous root system. The water hyacinth has striking light blue to violet flowers located on a terminal spike. Water hyacinth is a very aggressive invader and can form thick mats. If these mats cover the entire surface of the pond they can cause oxygen depletions and fish kills. Water hyacinths should be controlled so they do not cover the entire pond1. Distribution: Southern US Back to Floating Plant Menu

(1) White Water Lily – Nymphaea spp. • The White Water Lily is a perennial plant that often forms dense colonies. The leaves arise on flexible stalks from large thick rhizomes. The leaves are round, bright green, 6 to 12 inches in diameter with the slit about 1/3 the length of the leaf. Leaves usually float on the water's surface. Flowers arise on separate stalks, have brilliant white petals (25 or more per flower) with yellow centers. The flowers may float or stick above the water and each opens in the morning and closes in the afternoon. White water lily can spread from seeds or the rhizomes1. Distribution: Throughout North America Back to Floating Plant Menu

Yellow Water Lily – Nuphar spp. • Yellow Water Lilies are perennial plants that arise on flexible stalks from rhizomes and large fleshy roots that can resemble bananas. Leaves are oval heart-shape, 3 to 6 inches in diameter, shiny dark green on top and reddish-purple underneath Leaves float on the surface and are seldom emergent. Flowers are large (2 1/2 to 4 inches) bright yellow and usually stand above the water on separate stalks. Yellow water lilies can reproduce from seeds or by spreading of the rhizomes1. (1) (1) Distribution: Throughout North America Back to Floating Plant Menu

Submersed Aquatic Plants Click on a picture to select a plant Bladderwort Coontail Curly-leaf Pondweed Elodea Eurasian Watermilfoil Richardson Pondweed Sago Pondweed Tapegrass Back to Aquatic Plant Menu

(4) (4) Bladderwort – Utricularia vulgaris • Bladderwort is a submersed aquatic plant that floats freely throughout the water and have no true roots. The bladders that occur on the stems and leaves of all the Utricularia species helps to distinguish these weeds from any other floating or submerged aquatic weeds4. Distribution: Throughout Northern Hemisphere Back to Submersed Plant Menu

(10) Coontail – Ceratophyllum demersum • Coontail (sometimes called hornwort) is a dark olive-green, rootless submerged perennial plant that often forms dense colonies. Leaves are relatively stiff, whorled with many forks and small teeth along one edge. The tips of branches are crowded with leaves giving it a “coontail” resemblance. Coontail reproduces by seeds and fragmentation1. Distribution: Worldwide Back to Submersed Plant Menu

(4) (10) Curly-leaf Pondweed – Potamogeton crispus • Curly-leafed pondweed is a perennial plant that is native to Europe and gets it name from the rippled or wavy nature of its submerged leaves. The leaves are 3/4 to 4 inches long and ¼ to ½ inch wide. Mature leaves are toothed with a distinct midrib with paired parallel lateral veins, nearly translucent. Fruits are seldom found. There are small “bur” like reproductive structures at the base of some leaves. Curly-leafed pondweed can be an aggressive invader that can cover large portions of ponds1. Distribution: Nearly Worldwide Back to Submersed Plant Menu

(1) Elodea - Egeria spp. • Brazilian elodea (Egeria) looks very much like a larger, more robust version of its commonly-found native relative, Elodea canadensis (Canada Waterweed)5. Egeria is native to South America but has become naturalized in much of the Southeastern U.S. The dark green lance-like leaves are in whorls of 4 to 6 which become more dense near the tip of the stem (near the surface). Leaves are about ½ inch wide and from ¾ to 1 ¼ inches long with finely toothed margins. Flowers are white about 3/8 to ¾ inches in diameter on short stalks which commonly are emergent. Egeria is often confused with the native Elodea or the non-native Hydrilla. Hydrilla has one or more teeth on the underside of the midrib, neither Elodea nor Egeria have these midrib teeth. The teeth make Hydrilla feel rough when drawn through your hand from base to tip1. Distribution: Areas of North America Back to Submersed Plant Menu

(2) (1) (3) Eurasian Watermilfoil – Myriophyllum spicatum • Eurasian Watermilfoil is considered one of the most aggressive and problematic plants in North America because of the dense colonies which it forms. The stems are multi-branched, somewhat reddish in color, with gray-greenish feather-like leaves. The leaves are in whorls of 3 to 5 around the stem with each leaf divided into 12 or more pairs of thin thread-like leaflets. Reddish flowers are borne on leafless spikes that rise above the surface a few inches. Eurasian watermilfoil is non-native and should not be spread1. Distribution: Widespread in North America Back to Submersed Plant Menu

Richardson Pondweed has densely spaced, lance shaped leaves, 2-13 cm long, 1-3 cm wide, and have wavy often curved backwards margins. Stem often branched to 1 m long. Flowers in 4-12 whorls on short spikes. Flower stalks generally just longer than the spike, but sometimes much longer11. (10) Richardson Pondweed – Potamogeton richardsonii Distribution: Widespread throughout North America (10) Back to Submersed Plant Menu

(1) (10) Sago Pondweed – Potamogeton pectinatus • Sago pondweed is a perennial plant that has no floating leaves. The stems are thin, long and highly branching with leaves very thin and filament-like, about 1/16 of an inch wide and 2 to over 12 inches long tapering to a point. The fruit is nut-like 1/8 to 1/4 inches long and 1/10 to 1/8 inches wide1. Distribution: Worldwide Back to Submersed Plant Menu

(10) (1) Tapegrass - Vallisneria americana • Tapegrass, Eelgrass, or Wild Celery are all common names for Vallisneria. Tapegrass is a rooted submerged plant often found in flowing water. It has long, thin, ribbon-like leaves (1/2 – ¾ inches wide) that are commonly 3 to 4 feet long. The vein pattern in the leaves of eelgrass is very distinctive and resembles celery. Tapegrass has a vast rhizome system that allows it to form dense colonies and usually excludes other submerged plants1. Distribution: Throughout most of North America Back to Submersed Plant Menu

Emergent Aquatic Plants Click on a picture to select a plant Arrowhead Bulrush Cattail Fanwort Horsetail Pickerelweed Purple Loosestrife Sedges Smartweed Water Plantain Water Stargrass White Water Buttercup Back to Aquatic Plant Menu

Arrowhead – Sagittaria spp. • There are many species of Sagittaria but all are perennial plants that have arrowhead-shaped leaves. Usually leaves have 3 points giving it the arrowhead shape but some are narrow and almost grass-like. Arrowheads can grow in shallow water or in wet areas. Leaves grow in clusters from the base and can be from less than a foot tall to over 4 feet. Leaf petioles are long, often spongy and have a milky-like fluid if crushed. Rhizomes can be extensive and some species have large tubers off the roots. Flowers are borne on separate stalks above the water in whorls of three and are usually white to light pink with three petals. Arrowheads spread rapidly by seeds and extensive rhizomes1. (1) Distribution: Southern Canada and US Back to Emergent Plant Menu

(1) (1) Bulrush - Scirpus spp. • There are several species of bulrushes. Bulrushes are perennial grass-like plants and can grow to 10 feet tall in shallow water or in moist soils. Soft-stem bulrush can grow to 10 feet and grows in dense colonies from rhizomes. Soft-stem bulrush has a round (in cross section), light gray-green, relatively soft stem that comes to a point with no obvious leaves (only sheaths at the base of the stems). Flowers usually occur just below the tip of the stem1. • Giant bulrush can also grow to 10 feet, is dark green with a hard, triangular stem and no obvious leaves (sheaths at the base of the stems)1. Distribution: North America to Worldwide Back to Emergent Plant Menu

(1) Cattail - Typha spp. • Cattails have flat to slightly rounded leaves that twist slightly over their length and can grow to 5 or 10 feet in height. Flowers form a dense dark brown, cigar-shaped at the end of spikes (called the catkin). Cattails can be partially submerged or in boggy areas with no permanently standing water. Cattails spread rapidly because their seeds blow in the wind and float on the water's surface and vegetatively they spread from underground rhizomes1. Distribution: Worldwide Back to Emergent Plant Menu

Fanwort –Cabomba caroliniana • Fanwort is a rooted submersed plant. It may have submersed and floating leaves of different shapes. Fanwort generally grows in 3-10 ft of water, and is found in ponds, lakes and quiet streams. Fanwort stems are long and much-branched. Fanwort has fan-like underwater leaves, which are about two inches across. The submersed leaves are frequently divided, and are arranged oppositely or in whorls along the stem. The floating leaves are small, diamond-shaped, and are infrequent. Fanwort flowers are white to pink to purplish and are about 1/2 inch across. The flowers are on stalks which arise from the tips of the stems10. (13) Distribution: Mostly Eastern US (10) Back to Emergent Plant Menu

(1) (1) Horsetail – Equisetum hyemale • Horsetail is a perennial plant with dark-green hollow, jointed or segmented stems 1/4 to 1/2 inch tick with no true leaves. Stems may be singular or have whorls of branches. Only single stems produce the cone-shaped spore producing body at the tip. Horsetails can be standing in water or in wet areas. Horsetail stems contain silicon crystals (i.e. sand) embedded in its tissue. This gritty texture gives it a common name of "scouring rush“1. Distribution: Northern Hemisphere Back to Emergent Plant Menu

Pickerelweed – Pontederia spp. • Pickerelweed is a perennial plant that can grow up to 3 1/2 feet tall. Leaves are shiny green, heart-to-lance shaped(up to 7 inches long) singly attached to a long petiole which grow in a rosette from the roots. Each stem can produce a terminal flower spike 3 to 4 inches long. The numerous tubular flowers on the spike are violet-blue in color. Each flower lasts only one day. Pickerelweed reproduces from seeds and rhizomes1. Distribution: Temperate North and South America (1) Back to Emergent Plant Menu

(5) Purple Loosestrife - Lythrum salicaria • Purple loosestrife is a perennial, emergent aquatic plant. As many as 30 -50 herbaceous, erect, annual stems rise to about nine feet tall from a persistent perennial tap root and spreading rootstock. The showy, magenta flowering stems end in a 4-16 inch flowering spike. Purple loosestrife is invasive and competitive and unavailing to native wildlife. It can quickly adapt to environmental changes and expand its range to replace native plants5. Distribution: Throughout North America and areas Worldwide Back to Emergent Plant Menu

Sedges – Carex spp. • There are many types of sedges (over 100) and they are difficult to identify without using detailed botanical keys. In general, sedges are perennial plants that resemble grasses, grow in shallow water or moist soils, and can reach 4 feet in height. Sedges often grow in thick clusters. Stems of sedges are usually triangular. Spikes occur on the upper sections of the plant and can be single or in groups1. Distribution: Worldwide (1) Back to Emergent Plant Menu

Smartweed – Polygonium spp. • Smartweed is a perennial plant that forms dense colonies in shallow water or moist soils and can grow to 3 feet tall. Stems are jointed or have swollen leaf nodes that are surrounded by a tubular sheath. Leaves are alternate, lance-shaped up to 4 inches long but usually less than 1/2 inch wide. Flowers are on spikes at the end of stems (often numerous spikes on the same plant). Flowers begin as greenish then turn whitish or a light pink in color as they mature. Fruits are flat, triangular (1/8 inch), dark brown to black1. (10) Distribution: Nearly Worldwide Back to Emergent Plant Menu

(11) (11) Photograph by Clayton Antieau Water Plantain – Alisma spp. • These perennial plants typically grow on wet soil or in shallow water. Look for parallel veined leaves rising from the plant base. The small white or occasionally pink flowers occur on delicate stalks arranged in whorls around the main flower stalk. Stiff leaves generally stand above the water surface, but young plants often have ribbon-like underwater leaves. What appear to be stems are actually long leaf stalks. The stem is a bulb-like, usually buried in sediment. White to pinkish individual flowers to 7 mm across. They occur in whorls on slender branches arranged around a central flower-stalk11. Distribution: Nearly worldwide Back to Emergent Plant Menu

Water Stargrass – Heterantheria dubia • Water Stargrass is grass-like with thin branching dark-green stems and alternate leaves with no prominent midvein. Water Stargrass can grow up to 6 feet long and can form floating colonies. Flowers rise above the surface and are bright yellow, star-shaped, with 6 narrow petals. Water Stargrass reproduces from seeds and through fragmentation1. Distribution: Throughout most of North America (1) (1) Back to Emergent Plant Menu

White Water Buttercup – Ranunculus Aquatilis • White water buttercup is an aquatic, perennial wildflower with submerged stems measuring from 10-100 cm long. The leaves alternate along the stems, the submerge leaves dissected into many needle-like segments. The lower leaves are typically sessile while the upper leaves may have petioles measuring up to 2 cm long. The floating leaves are similar to the lower leaves but are 5-15 mm long and nearly twice as wide, the blades shallowly to deeply 3-lobed and with toothed or lobed segments12. (12) Distribution: Throughout most of North America Back to Emergent Plant Menu

Other Online Aquatic Plant ID Guides • Virginia Tech Weed Guide: www.ppws.vt.edu/scott/weed_id/aquatics.htm • University of Florida Invasive Aquatic Plant ID Guide: http://aquat1.ifas.ufl.edu/photocat.html • Washington State Department of Ecology – Plant ID Manual Online: www.ecy.wa.gov/programs/wq/plants/plantid2/categories.html • Texas Agricultural Extension Service – Aquaplant ID: http://aquaplant.tamu.edu/Plant_Id.htm Back to Menu

Information and Image Sources 1Texas Cooperative Extension: http://aquaplant.tamu.edu/Floating%20Plants/Floating_Plant_Index.htm, Texas A & M University, Plant Identification, 2004 2Non-Native Invasive Aquatic Plants in the United States: http://aquat1.ifas.ufl.edu/seagrant/myrspi.jpg, Center for Aquatic and Invasive Plants, University of Florida, 2001 3Simmons, Kent. Eurasian Water Milfoil: http://io.uwinnipeg.ca/~simmons/ysesp/exotic4.htm, University of Winnipeg, 2004 4Virginia Cooperative Extension. Aquatic Weeds: www.ppws.vt.edu/scott/weed_id/aquatics.htm, Virginia Tech, 2004 5Problem Aquatic Plants: www.wapms.og/plants/index.html, Western Aquatic Plant Management Society , 2004 6Egmond, Wim Van. Algae:http://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org.uk/pond/, On-view.net Ltd., Microscopy UK, 1995 7Parmentier, Jan. Asterionella: http://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org.uk/pond/, On-view.net Ltd., Microscopy UK, 1995 8Morgan, Mike. Some Observations on a Freshwater Algae: http://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org.uk/pond/, On-view.net Ltd., Microscopy UK, 2000 9MSU Extension Bulletin. Aquatic Plant Identification and Management: http://www.pested.msu.edu/BullSlideNews/bulletins/pdf/2437/E-2437_Chap5.pdf, Michigan State University, 2004 10Aquatic and Wetland Plant and Invasive Plants: http://aquat1.ifas.ufl.edu/photocat.html, Center for Aquatic and Invasive Plants, University of Florida, 2001-2002 11Aquatic Plant Identification Manual for Washingtons Freshwater Plants: http://www.ecy.wa.gov/programs/wq/plants/plantid2/categories.html, Washington State Department of Ecology * distribution info found here 12Wright, John. Wildflowers of Ontario – White Water Buttercup: www.wildflowers.reach.net, 2001. 13Mehrhoff, Lesli, J. Invasive Plant Atlas of New England http://webapps.lib.uconn.edu/ipane/jpg/images.cfm?unique_identifier=uconn_ipane_cabomcarol_02, 2003 Exit to SHAC Home Back to Menu

Common Aquatic Weeds & Algae of Canada and U.S.A.