Milfoil - Myriophyllum heterophyllum
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Variable-leaf milfoil is a rooted perennial and submersed except for
the flowering spikes that are emersed and from 5 to 25 cm long. The submersed
stems are stout (up to 8 mm in diameter), reddish, often with numerous
branches. Submersed leaves are 4 to 6, whorled, up to about 6 cm long
with 6 to 14 pairs of narrow segments. The emersed flowering spikes have
bright green, leaf-like bracts that are in whorls of 4 to 6 with toothed
to entire margins. The bracts are 4 to 12 mm long and more than twice
the length of the small flowers that are borne in the axils of the leaf-like
bracts. The fruit is hard, four-lobed, 1 to 1.5 mm long, and splitting
into four distinct segments (mericarps).
Variable-leaf milfoil is found in ponds, lakes, streams, ditches and
spring-fed swamps and sloughs. Reproduction is by seed and fragmentation.
Regrowth occurs from rhizomes rooted in the hydrosoil. Plants stranded
on mud and dewatered shorelines often develop numerous, erect spikes that
are readily visible due to the bright green leaf-like bracts. Variable-leaf
milfoil also is occasionally sold as an aquarium plant (Tarver et al.
Myriophyllum heterophyllum can be an aggressive plant in some situations
and may interfere with water movement, boating, swimming, fishing and
other recreational activities (Tarver et al. 1986, Crow and Hellquist
Links to more information
Website, video, and graphics by Rob Nelson
For more information on this plant or management please contact US Army Corp of Engineers