Practical information to identify and manage non-native, invasive plants
The Quiet Invasion:A Guide to Invasive Plants of the Galveston Bay Area
Myriophyllum spicatum
| USDA Symbol: | MYSP2 |
| ITIS TSN: | 27039 |
| Presence: | Future Threats |
| Habitat: | Aquatic |
| Native Range: | Europe, Asia, and Northern Africa |
Toxic Characteristics
This species is not known to be toxic.Geographic Distribution
Present in nearly every state east of the Mississippi River and as well as rivers and streams of the Great Plains and western states. Established in eastern and central Texas, but is not known to be established in the Lower Galveston Bay watershed.Introduction Pathways
Introduced to the United States in the 1940s. By some accounts, it may have been introduced as early as the 1880s. This species is a popular aquarium plant and can be dispersed by movement of boats and trailers.Specific Primary Habitats
Requires a submersed aquatic environment. Tolerates a wide range of salinities and temperatures, but requires plenty of light. Nutrient-rich, slow-moving waters are prone to invasion.Identifying Characteristics
Stems are long and slender, often branching near the water surface. Growing tips are often red, and stems generally reach 6-9 feet in total length. Leaves are compound, feather-like, and grouped in whorls of 4 at stem nodes where they consist of several multi-divided leaflets. Flowers, small and pink, appear above the water on terminal red-colored stems and are 1.5-3 inches long.Reproduction Characteristics
Seed dispersal and germination are not significant means of reproduction. This species propagates by budding from stem fragments or at stem nodes, which later root upon contact with soil; also roots from rhizomes.Growth Characteristics
Once established in substrate and temperatures warmer than 60 Fahrenheit, Eurasian watermilfoil rapidly grows toward the water surface. Stems may grow up to 30 feet in length. Regrowth occurs from root crowns in successive years.Ecological, Economic, or Social Impact
Eurasian watermilfoil forms thick stands within and above the water column, trapping light and shading out native vegetation. It will stagnate water by increasing pH and temperature, lowering dissolved oxygen, thus promoting mosquito breeding habitat.Suggested Control Methods
Aquatic herbicides such as diquat, complexed copper, and endothall dipotassium salt are effective, while fluridone is selective. Water level control is also effective. Care should be taken when mechanically harvesting; fragmentation promotes spread.|
Native Species Alternatives
Below is a list of alternative plants that are native to the area:
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Lists
This species belongs to the following lists:
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Images
To view a larger version of an image, click on the thumbnail. Dense canopy of eurasian watermilfoil on the surface of a lake. Photo courtesy of Robert L. Johnson, Cornell University, www.forestryimages.org; Image Number 0002002. |
 Cluster of stems and leaves of eurasian watermilfoil at water surface. Photo courtesy of Alison Fox, University of Florida, www.forestryimages.org; Image Number 1624031. |
 Single stem of eurasian watermilfoil showing whorls of compound leaves. Photo courtesy of Robert H. Mohlenbrock, USDA NRCS PLANTS Database, www.forestryimages.org; Image Number 2308040. |