Graves Lovell, AL DCNR

Parrot-Feather

Myriophyllum aquaticum (Vell.) Verd.
Water milfoil family (Haloragaceae)

Origin: South America

Background
Parrot-feather was introduced to the United States in the Washington, DC area about 1890. Commonly sold for aquaria and aquatic gardens, it has escaped to become invasive in ponds and other calm water bodies in this region.

Distribution and Habitat
Parrot-feather occurs in at least 26 states throughout the United States. It is limited to non-tidal, freshwater, slow-moving water bodies including tributaries, ponds, lakes and canals. It prefers good light, slightly alkaline and high-nutrient environments.

Ecological Threat
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

• Plant: aquatic plant with stout elongate stems suspended in the water column and/or floating; both stems and submerged leaves may be reddish tinted; gray-green tips of the stems with leaves may protrude above the water.
• Leaves: well-developed, finely pinnately divided, in whorls of mostly five with smooth leaf margins.
• Flowers, fruits and seeds: flowers and fruits, if present emerge from axils of leaves.
• 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.
• Look-alikes: many species of submerged aquatic plants including non-native invasive Eurasian water-milfoil (Myriophyllum spicatum), and native species such as Northern water-milfoil (M. sibiricum), coontail (Ceratophyllum dmersum) and water marigold (Megalodonta beckii).

John M. Randall, TNC

Graves Lovell, AL DCNR

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 parrot-feather is ongoing.

Native Alternatives
Aquatic plant species are difficult to tell apart to the untrained eye. Contact your state natural resource agency, native plant society or other resource (see References) for assistance.