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Milfoil comparison table
Milfoil comparison table

Myriophyllum alterniflorum


Alternate-flowered Milfoil colony
Alternate-flowered milfoil in-situ
(growing with a native pondweed)

Description: Alternate-flowered water-milfoil has two distinct leaf types: submersed leaves and emergent leaves (called bracts). Alternate-flowered milfoil is the smallest of the water-milfoils, having submersed leaves typically less than 1 cm long. The leaves are finely feather-divided (3 to 7 thread-like leaflet pairs per leaf), cupped slightly upward, and arranged in strict whorls (3 to 5 leaves per whorl) that are noticeably spaced along a slender stem. Both leaves and stems may be reddish. The tiny flowers occur in the axils of the bracts, in a generally alternate arrangement, on an emergent spike that projects less than 5 cm above the water. (The arrangement of flowers and bracts may be opposite near the bottom of the spike.) The bracts are entire or slightly serrated, and are the same length or slightly longer than the flowers and fruits. Toward the end of the growing season, winter buds (or turions) comprised of small stiff leaves are formed along the submersed stems.

alternate-flowered water-milfoil Range Map
U.S. range map of
alternate-flowered water-milfoil

U.S. Range: Alternate-flowered water-milfoil is native to Maine, new England and to other parts of the United States.

Look Alikes: The combination of miniature form, strictly whorled submersed leaves spaced along slender stems, and flowers alternately arranged on the flower spike generally help to distinguish this species from other water-milfoils.

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Alternate-flowered water Milfoil in-situ Alternate-flowered water Milfoil range map Alternate-flowered water Milfoil fruit
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