Myriophyllum pinnatum Troy Weldy

Myriophyllum pinnatum
Troy Weldy

Dicotyledoneae (Dicots)
Haloragaceae (Water-Milfoil Family)
State Protection
Federal Protection
Not Listed
State Conservation Status Rank
Global Conservation Status Rank


Did you know?

This is one of only two species of Myriophyllum in the state that has both alternate and whorled leaves. The other one is Myriophyllum farwellii, also rare. It's common name comes from the feathery appearance of its leaves and the genus name means numberless (Myrio) leaves (phyllum) referring to the many divided leaves (Fernald 1970).

State Ranking Justification

There are only four existing populations and one of these may have been extirpated from the incursion of seawater. There are seven historical populations from the first half of the 20th century in heavily developed areas and most of these are probably extirpated.

Short-term Trends

There has been a slight decline in existing populations as one site has probably been extirpated by the incursion of saltwater.

Long-term Trends

This species has always existed in low numbers in the state. Historical records from western Long Island have probably disappeared while new populations in the Hudson Highlands and eastern Long Island have been discovered.

Conservation and Management


Freshwater ponds close to the ocean may be affected by saltwater infiltration during storm events.

Conservation Strategies and Management Practices

Protect its pond and river habitat by preventing the alteration of water quality.



In New York this species has been discovered in and along the shores of small ponds and ditches as well as large lakes (Lake George) and the Hudson River. It apparently can tolerate sandy, rocky, or clayey substrates (New York Natural Heritage Program 2007). Peaty or muddy shores or in shallow waters (Fernald 1970).

Associated Ecological Communities

  • Coastal plain pond* (guide)
  • Coastal plain pond shore* (guide)
  • Ditch/artificial intermittent stream
  • Inland non-calcareous lake shore*
  • Oligotrophic pond
  • Riverside sand/gravel bar (guide)
  • Shallow emergent marsh (guide)

Associated Species

  • Bidens cernua (nodding beggar-ticks)
  • Cyperus erythrorhizos (red-rooted flat sedge)
  • Echinochloa crus-galli (Eurasian barnyard grass)
  • Elatine minima (lesser waterwort)
  • Eleocharis acicularis (needle spike-rush)
  • Eleocharis elliptica (elliptic spike-rush)
  • Hypericum mutilum
  • Persicaria hydropiper (water-pepper)
  • Rhynchospora capitellata (brownish beak sedge)
  • Schoenoplectus purshianus
  • Scirpus pu


New York State Distribution

Most of our occurrences for Green Parrot's-feather are on Long Island, but it has also been found in Lake George (the Adirondacks), and in the Hudson River as far north as Washington County.

Global Distribution

Green Parrot's feather is found in most of the southern and central U.S. states, from Florida to New Mexico in the south. It reaches its northern limit in the Dakotas, Saskatchewan and British Columbia in the west, New York and Massachusetts in the east. It is a species of conservation concern throughout much of the northern part of its range.

Best Places to See

  • Sterling Forest Sandy Beach Lake (Orange County)

Identification Comments

General Description

This is an aquatic, perennial plant of shallow water, sometimes also found growing along shorelines. The leaves develop in different form depending on whether they are above or below water. The submerged leaves are at least partly alternate, pinnate and featherlike, and 1-3 cm long. In the terrestrial form, and the above water (emersed) portion of aquatic plants, the leaves are in whorls. The flowers are not in separate spikes but arise individually along the stem just above each leaf, on emersed stems. The small, (2 mm) hard fruits are 4-parted and deeply lobed, with longitundinal ridges.

Similar Species

Myriophyllum farwellii, the only other species of Myriophyllum in New York with alternate leaves, has flowers borne in the axils of submersed leaves.

Best Time to See

The fruits mature in early July, and may persist on the stems into October.

  • Flowering
  • Fruiting

The time of year you would expect to find Green Parrot's Feather flowering and fruiting in New York.

Green Parrot's Feather Images


Green Parrot's Feather
Myriophyllum pinnatum (Walt.) B.S.P.

  • Kingdom Plantae
    • Phylum Anthophyta
      • Class Dicotyledoneae (Dicots)
        • Order Haloragales
          • Family Haloragaceae (Water-Milfoil Family)

Additional Common Names

  • Milfoil


  • Myriophyllum scabratum Michx.
  • Potamogeton pinnatum Walt.

Additional Resources

Best Identification Reference

Crow, Garrett E. and C. Barre Hellquist. 2000. Aquatic and Wetland Plants of Northeastern North America: A revised and enlarged edition of Norman C. Fassett's a Manual of Aquatic Plants. Volume One: Pteridophytes, Gymnosperms, and Angiosperms: Dicotyledons. The University of Wisconsin Press. Madison, Wisconsin. 536 Pages.

Other References

Aiken, S.G. 1981. A conspectus of Myriophyllum (Haloragaceae) in North America Brittonia 33(1):57-69.

Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.

Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.

New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.

New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.

Ogden, E.C. 1974. Anatomical patterns of some aquatic vascular plants of New York. New York State Museum Bull. 424.

Taylor, Norman. 1915. Flora of the vicinity of New York. Memoirs of the New York Botanical Garden vol. V. New York, NY.

Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research University of South Florida]. New York Flora Association, Albany, New York

Weldy, Troy W. and David Werier. 2005. New York Flora Atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research. University of South Florida]. New York Flora Association, Albany, NY. Available on the web at (


About This Guide

Information for this guide was last updated on: December 11, 2008

Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Myriophyllum pinnatum. Available from: Accessed March 20, 2019.

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