Mike Naylor, MD DNR
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Parrot Feather Watermilfoil
Myriophyllum aquaticum
Origin: South America
Background
Parrotfeather was introduced to the United States in the
Washington, DC area about 1890. Commonly sold for aquaria
and aquatic gardens, it has escaped to some freshwater
ponds in this region.
Distribution and Ecological Threat
Parrotfeather occurs in at least 26 states throughout the
United States, and is limited to non-tidal fresh waters.
It can form dense mats and compete with native aquatic
plants, especially in shallow ponds. It also provides
habitat for mosquito larvae, impedes boats and clogs
drainage ditches.
Description and Biology
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Plant: aquatic plant with stout stems; both stems and
submerged leaves may be reddish tinted; gray-green tips
of the stems with leaves may protrude above the water.
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Leaves: are finely divided, pale whitish green in
color, in whorls of mostly five with smooth leaf
margins.
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Flowers, fruits and seeds: flowers in axils of
submerged leaves; fruits up to 1/8 inch long.
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Spreads: vegetatively from whole plants or fragments;
it can be dispersed by people dumping aquaria into
rivers and ponds and by animals carrying fruits and
fragments on their bodies.
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Look-alikes: coontail (Ceratophyllum demersum),
hydrilla (Hydrilla verticillata), Eurasian
watermilfoil (Myriophyllum spicatum, non-native,
invasive), and possibly elodeas.
Prevention and Control
Attempting control by manual or mechanical means tends to
spread the plants and should only be conducted in small,
contained water bodies. Draining a pond in the summer
achieved control in one instance, but draining may not
achieve control in winter. Control with herbicides is
difficult because the emergent stems and leaves have a
waxy cuticle that repels herbicides. Research into
biological control of parrotfeather is ongoing.
Peter Bergstrom, USFWS
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Peter Bergstrom, USFWS
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Peter Bergstrom, USFWS
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Native Alternatives
Some aquatic nurseries carry native and non-invasive
alternatives. However, due to the similarity in appearance
among aquatic plants to the untrained eye, they are easily
confused. Contact your state natural resource agency,
native plant society or other resource (see
reference section) for assistance in locating species
appropriate to your location and site conditions.
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