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Invasive Species: Aquatic Plants

Invasive Aquatic Plants

Species that are not native and also have the potential to harm human health or to harm natural, agricultural or silvicultural resources can be listed as prohibited or restricted by the State of Michigan. If a species is prohibited or restricted, it is unlawful to possess, introduce, import, sell or offer that species for sale as a live organism, except under certain circumstances.

African Oxygen Weed

(Lagarosiphon major)

Prohibited in Michigan

African oxygen weed is a dark green submerged aquatic plan. It has alternating leaves that curl downwards and forms a dense mat up to three feet thick. The stems grow up to 20 feet long with 'J' shaped curve.

More information: African oxygen weed

Brazilian Elodea

(Egeria densa - synonyms: Elodea densa, Anacharis densa and Philotria densa)

Watch List - Prohibited in Michigan

Brazilian elodea is a bushy aquatic plant with dense whorls of bright green leaves. It can be found in ponds, lakes, and sluggish rivers and streams.


More information: Brazilian elodea

Carolina Fanwort

(Cabomba caroliniana)

Prohibited in Michigan

Carolina fanwort is a submerged aquatic plant, rooted in the mud of stagnant or slow-flowing water. The underwater leaves are approximately two inches across and divided into fine branches. The flowering branches grow above the water surface with diamond shaped leaves. The flowers are small and range from white to pale yellow.

More information: Carolina fanwort

Curly-Leaf Pondweed

(Potamogeton crispus)

Restricted in Michigan

Curly-leaf pondweed is submersed, perennial herb with thick roots and a flowering spike that grows above the water's surface. The leaves are dark green with wavy, serrated margins. It starts growing in fall and winter, flowers in late spring and dies in late July.

More information: Curly-leaf pondweed


(Cylindrospermopsis raciborskii)

Prohibited in Michigan

Cylindro is one of many species of blue-green algae and is considered invasive and harmful. The blooms are just below the water surface of fresh water habitats and may appear as foggy green/yellow water. Cylindro has been documented in many inland lakes and reservoirs around the Great Lakes region.

More information: Cylindro

Didymo (Rock Snot)

(Didymosphenia geminata)

Didymo (also known as "rock snot") looks and feels like white or tan/brown wet wool. It ranges from small cotton ball-sized patches to thick blankets and long ropy strings that flow in currents. Although it is often referred to as "rock snot," didymo is not slimy.

More information: Didymo

Eurasian Watermilfoil

(Myriophyllum spicatum)

Restricted in Michigan

Eurasian watermilfoil is an aquatic plant with stems that are whitish-pick to reddish-brown, leaves that are greyish-green with finely divided pairs of leaflets that are 1/2 - 2 inches long that give the plant a feathery appearance. The leaves are arranged in whorls of 3-6. Yellow or reddish flowers with 4 parts on a projected spike sitting 2-4 inches above the water.

More information: Eurasian watermilfoil

European Frog-bit

(Hydrocharis morsus-ranae)

Prohibited in Michigan

European frog-bit has kidney-shaped to heart-shaped leaves and a single white flower with three round petals and a yellow center. This plant can be found free-floating or rooted in shallow water. Its habitat includes slow moving rivers, sheltered inlets, ponds, and ditches.

More information: European frog-bit

European Water Clover

(Marsilea quadrifolia)

Watch List

The European water clover resembles a large four leaf clover, with thin green stalks bearing a single leaf. It can be found in shallow, slow-moving waters.

More information: European water clover

Flowering Rush

(Butomus umbellatus)

Restricted in Michigan

Flowering rush is a perennial, aquatic herbaceous plant that typically grows in shallow sections of slow moving streams or rivers, lake shores, irrigation ditches and wetlands. The leaves have triangular cross section, are narrow, and twist toward the tip. When flowering the flowers grow in round umbrella-like clusters of 20-50 flowers, 6 light pink to rose colored petals per flower, 9 stamens per flower. 

More information: Flowering rush

Giant Salvinia

(Salvinia molesta, auriculata, biloba, or herzogii)

Prohibited in Michigan

Giant salvinia is a free-floating aquatic fern with oblong leaves that are 1/2 - 1 1/2 inches long and vary in color from green to gold to brown. The leaves have arched, white hairs resembling egg beaters. The submerged fern fronds are stringy and root-like, but the plant has no real roots. Leaves grow vertically and curl creating a chain-like structure.

More information: Giant salvinia


(Hydrilla verticillata)

Watch List - Prohibited in Michigan

Hydrilla is a submerged aquatic plant with generally green leaves whorled in a group of 4-8. They have very slender stems that grow up to 30 feet long and branch out considerably near water surface.

More information: Hydrilla

Parrot Feather

(Myriophyllum aquaticum - synonyms: Myriophyllum brasiliensis, Myriophyllum brasiliense, Myriophyllum proserpinacoides and Enydria aquatica).

Note: "Dwarf parrot feather" and "dwarf red parrot feather" are common names for a dwarf selection sold in trade. 

Watch List - Prohibited in Michigan

Parrot feather has spikes of stiff, feathery leaves that grow in whorls of 4-6. It has bright green upper stems that emerge up to one foot above water and small inconspicuous white flowers where leaves attach to the section of stem above water.

More information: Parrot feather

Phragmites (Common Reed)

(Phragmites australis)

Restricted in Michigan

Invasive phragmites (also known as common reed) is a warm-season perennial grass with a rigid hollow stem and leaves that are flat, smooth, and green to grayish-green. The flowers grow as dense branched clusters on the end of each stem that are open and feathery at maturity. The plant ranges in height from 6-13 feet.

More information: Phragmites

Purple Loosestrife

(Lythrum salicaria)

Restricted in Michigan

Purple loosestrife is a perennial herb with a woody square stem covered in downy hair. It varies in height from 4 - 10 feet. It has leaves that are arranged in pairs or whorls and magenta flower spikes with 5 - 7 petals per flower that are present for most of the summer.

More information: Purple loosestrife

Starry Stonewort

(Nitellopsis obtusa)

Prohibited in Michigan

Starry stonewort is a submerged aquatic plant that invades lakes, ponds, reservoirs, and slow moving rivers. It has whorls of 4-6 branchlets/leaves with blunt tips. They have star-shaped bulbils produced at the nodes, generally 3-6 mm wide. They can reach up to 33 inches in length.

More information: Starry stonewort

Water Chestnut

(Trapa natans)

Watch List - Prohibited in Michigan

Water chestnut has green floating leaves with sharply serrated edges that form a densely crowded rosette. They produce small, white 4-petaled flowers and a woody nut surrounded by sharp barbed spines.

More information: Water chestnut

Water Hyacinth

(Eichhornia crassipes)

Watch List

Water hyacinth is a free-floating perennial herb with short, bulbous leaf petioles and has round, leathery leaves arranged in whorls of 6-10. It has distinctive air bladders that keep the leaves afloat.

More information: Water hyacinth

Water Lettuce

(Pistia stratiotes)

Watch List

Water lettuce is a free-floating plant with a rosette of leaves that resembles an open head of lettuce. The leaves are thick, ridged, rounded at the end, light green, and have short, white hairs. It produces small, white to pale green flowers. Many feathery roots dangle under the rosette.

More information: Water lettuce


Watch List

(Ludwigia grandifolia, Ludwigia peploides and Ludwigia hexapetala) 

Invasive water-primrose species are aquatic plants that can thrive and spread in shallow water areas including wetlands and shorelines. Water-primrose can grow quickly, with both upright stems and horizontal runners crowding out important native vegetation. 

More information: Water-primrose

Water Soldier

(Stratiotes aloides)

Watch List - Prohibited in Michigan

Water soldier is a submerged aquatic plant that becomes buoyant during the summer. Its leaves are 40cm long, bright green, sword-shaped, have sharply serrated edges, and form a large rosette. The roots may or may not be attached to mud. This plant looks similar to an aloe plant, spider plant, or top of a pineapple.

More information: Water soldier

Yellow Floating Heart

(Nymphoides peltata)

Watch List - Prohibited in Michigan

Yellow floating heart has bright yellow flowers with 5 petals located above the surface of the water. Leaves are circular or heart shaped and are alternately arranged on the stem but oppositely on the flower stalk.

More information: Yellow floating heart