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Hybrid watermilfoil (Myriophyllum xspicatum)

Hybrid watermilfoil Description: Newly discovered hybrid of Eurasian watermilfoil (Myriophyllum spicatum) and native northern watermilfoil (M. sibiricum). This species can only be identified by its molecular composition.

Habit: Submergent aquatic perennial, commonly ranges from 1-3 m (3-10 ft) in length but may reach 4 m (33 ft), forms dense mats.

Leaves: Submerged, feather-like, 4-5 leaves with 9-21 threadlike pairs of leaflets whorled around stem at each node, bright green in color, limp when out of water.

Stems: Thick near the base, becoming more slender and branching near the water surface; usually 1-3 m (3-10 ft) long.

Flowers: Inconspicuous, yellow in color, 4-parted, flower spikes rise 5-10 cm (2-4 in) above water surface.

Fruit and seeds: Seed pod that contains 4 seeds.

Habitat: Have been found in large numbers of populations across North America. It has spread rapidly across the Great Lakes region over the past several years.

Reproduction: Vegetatively by fragmentation and creeping runners; seeds viable but not an important dispersal mechanism; unlike many aquatic plants, it does not produce turions.

Monitoring and rapid response: Monitor water bodies for new colonies. Public education and prevention is critical. Reduce nutrient enrichment where possible; hand pull or rake out colonies, removing all fragments; biological control with native herbivorous weevil (Euhrychiopsis lecontei) shows promise; herbicides show mixed results; check current research -treatment rapidly evolving. Permits are usually required for herbicide use in water bodies and wetlands. For information see MDEQs Aquatic Nuisance Control website at: https://www.michigan.gov/egle/0,9429,7-135-3313_3681_3710---,00.html

Credits: The information provided in this factsheet was gathered from Grand Valley State University Annis Water Resources Institute.

Individual species images that appear with a number in a black box are courtesy of the Bugwood.org network (http://www.invasive.org).Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (http://images.google.com).


Common Name:

Hybrid watermilfoil

Scientific Name:

Myriophyllum xspicatum

Family:

Haloragaceae
(Water milfoil)

Duration:

Perennial

Habit:

Aquatics

USDA Symbol:

NA