Myriophyllum heterophyllum, laxumInvasive water-milfoil hybrid variable + loose

Plant Community: Submersed

Depth: 1 to 5 m

Leaf Heterophylly: No

Leaf Arrangement: Whorled

Leaves/Whorl: 4 to 6, dense

Divided Leaf Pattern: Feathered

Leaflet Paris: 5 to 14

Flower Characteristic: Flower spike with bracts and flowers both alternate and whorled. Bracts divided and lobed or elongate and entire.

Degree of Invasiveness in Maine: Invasive 2

Look-alike Species: Other water milfoils, Water marigold, Coontail, Bladderwort, Water crowfoot, Fanwort, Mermaid-weed

Reproduction type: Rhizome, Root division, Fragmentation

Origin: Southeastern United States

THE PLANT: Aquatic plant; submersed; well-adapted; hardy; dense bottle-brush appearance

THE LEAVES: Submersed; feather-divided; densely spaced whorls; 5 to 14 leaflet pairs per leaf

THE STEM: Robust; reddish

THE FLOWERS: Alternate and whorled; no winter buds; does not flower every year

THE HABITAT: Still and flowing water, Under ice, Muck, silt, sand, gravel

KEY ID FEATURES: Dense bottle-brush appearance; bracts and flowers arranged alternately and whorled; bracts divided and lobed, elongate and entire

Credits: (c) GMRI