Mid-Atlantic Invaders Tool

Eurasian watermilfoil

Myriophyllum spicatum

L.

Taxon, Habit: Plant, Forb

Habitat: Aquatic

U.S. Nativity: Introduced

Species Synonym(s): None

Common Name(s): spiked watermilfoil

Family: Haloragaceae (Water Milfoil Family)

Family Synonym(s): None

Native Range (GRIN):

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Infestation

Leslie J. Mehrhoff, University of Connecticut

Plant

Alison Fox, University of Florida

Flower

Leslie J. Mehrhoff, University of Connecticut

Foliage

Graves Lovell, Alabama Department of Conservation and Natural Resources

Foliage

Graves Lovell, Alabama Department of Conservation and Natural Resources

Plant

Graves Lovell, Alabama Department of Conservation and Natural Resources

Plant

Leslie J. Mehrhoff, University of Connecticut

Plant

Robert L. Johnson, Cornell University

Seed

Steve Hurst, USDA NRCS PLANTS Database

Plant

USDA NRCS PLANTS Database , USDA NRCS PLANTS Database

Description

Appearance
Myriophyllum spicatum is a submersed aquatic plant that invades lakes, ponds, and other aquatic environments throughout the United States. The plants are rooted and the stems grow up to the water surface, usually reaching 3-10 ft. (0.9-3 m) in length and can be as much as 30 ft. (9.1 m) long.
Foliage
Leaves are bright green, finely dissected, and whorled. The delicate leaflets give this plant a feathery appearance.
Flowers
Myriophyllum spicatum has both male and female flowers on the same inflorescence. The female flowers are basal while the male flowers are located distally. The female flowers have a 4-lobed pistil and lack sepals and petals. The male flowers have 4 pink petals and 8 stamens.
Fruit
The very small globular fruit of Myriophyllum spicatum are indehiscent, and contain 4 seeds.
Ecological Threat
Myriophyllum spicatum requires stagnant to slowly moving water and can tolerate brackish conditions. It forms dense mats of leaves restricting light availability, leading to a decline in the diversity and abundance of native macrophytes. In addition, Myriophyllum spicatum displaces the native species of watermilfoil and reduces habitats for fish spawning and feeding. It is native to Europe, Asia, and northern Africa.

Uses

Landscape Ornamental Use (GRIN): No

All Uses (GRIN):

Distribution Map (EDDMapS)

Wetland Indicator

Summary: Eurasian watermilfoil (Myriophyllum spicatum) is a Aquatic species.

Atlantic and Gulf Coastal Plain (AGCP):

Mid-Atlantic Coastal Plain regions

Eastern Mountains and Piedmont (EMP):

Mid-Atlantic Piedmont and Mountain regions

Northcentral and Northeast (NCNE):

Northern parts of PA and NJ (and beyond)


Legend (data from U.S. Army Corps of Engineers)

OBL (Obligate wetland): Almost always occurs in wetlands (estimated probability > 99%) under natural conditions

FACW (Facultative wetland): Usually occurs in wetlands (estimated probability 67% - 99%), but occasionally found in non-wetlands

FAC (Facultative): Equally likely to occur in wetlands (estimated probability 34% - 66%) or non-wetlands

FACU (Facultative upland): Usually occur in non-wetlands (estimated probability 67% - 99%), but occasionally found in wetlands (estimated probability 1% - 33%)

UPL (Obligate upland): Occur almost always (estimated probability > 99%) in non-wetlands under natural conditions

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Rosidae
Order: Haloragales
Family: Haloragaceae
Genus: Myriophyllum
Subject: Myriophyllum spicatum L.

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