Photo credit: John M. Randall, The Nature Conservancy, Bugwood.org
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Species at a Glance
Parrot feather, also called Brazilian watermilfoil, is an herbaceous aquatic perennial and member of the watermilfoil family. It gets its name from its bright green feather-like leaves which are whorled around the stem and form thick suffocating mats. Only female parrot feather plants have been found in North America.
Leaves: Emergent leaves are robust, vibrant green, feathery, and covered with a waxy coating. They are arranged around the stem in whorls of 4-6 and are 2.5-5 cm (1-2 in) long with 10-18 leaflet pairs. Leaves become more closely arranged toward the growing tips of the plant. Limp submerged leaves are brownish to reddish, often appearing deteriorated. They are 1.5-3.5 cm (0.6-1.4 in) long with 20-30 divisions per leaf.
Flowers: Small (1.5 mm [0.06 in]) white-pinkish flowers appear between the leaf axils of female plants in the spring.
Stems/Roots: Long unbranched stems reach heights of 30 cm (12 in) above the water’s surface. When attached to a bank, they can extend out several yards over the water’s surface.
A close relative, Eurasian watermilfoil (Myriophyllum spicatum) is easily mistaken for the submerged leaves of parrot feather. Other look-a-likes include bladderworts, hornworts, mermaid weeds, water crowfoots, and other leafy milfoils. The emergent stems and leaves are the most distinct characteristics of parrot feather, as they can grow up to 30 cm (12 in) above the water surface and resemble small fir trees.
Parrot feather is hardy but prefers shallow, nutrient-rich, and slow-moving waters. It is most common in shallow water as a rooted plant but can also be found as a floating plant in deeper nutrient-enriched lakes.
Since all parrot feather plants in the United States are female, they spread exclusively by fragmentation. Therefore, human activities such as water gardening, boating, and fishing can easily spread fragments to new locations where they can grow into new plants.
Native to South America in the Amazon River, parrot feather was introduced as a garden plant in the 1800s. It has since spread throughout the United States and can be found in all Mid-Atlantic states.
Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.
Parrot feather forms thick mats that can shade out native plant and algae species, impact water flow, clog recreational waterways and irrigation canals, and alter the physical and chemical characteristics of lakes and streams.
Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).