Myriophyllum verticillatum

Whorled Leaf Water Milfoil

Whorled Leaf Water Milfoil, Photo Courtesy USDA Plants Database
Whorled Leaf Water Milfoil
Photo Courtesy USDA Plants Database

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Name:

  • Myriophyllum, from the Greek, murios (myrios), "countless, infinite", and fullon (phyllon), "leaf; foliage"; hence "many leaved"
  • verticillatum, from the Latin, verticillus, "the whirl of a spindle", hence "whorled"
  • Common name from the flowers in whorls at the base of the leaves
  • Other common names include: Green Milfoil, Whorled Water Milfoil, Krans-Tusindblad (Dan), Kiehkuraärviä (Fin), Quirliges Tausendblatt (Ger), Tjarnamari (Is), Kranstusenblad (Nor), Stolístok Praslenatý (Slovak), Kransslinga (Swe)

Taxonomy:

  • Kingdom Plantae, the Plants
    • Division Magnoliophyta, the Angiosperms (flowering plants)
      • Class Magnoliopsida, the Dicotyledons
      • Subclass Rosidae
        • Order Haloragales
          • Family Haloragaceae, the Water Milfoils
            • Genus Myriophyllum, the Water Milfoils
  • Taxonomic Serial Number: 27040

Description:

  • A free floating, submerged, perennial aquatic herb.
  • Leaves in whorls of 4-5, smooth, ¼"-1¾" long, with 9-13 thread-like segments along each side of the midrib yielding a highly dissected, feather-like form. Emergent leaves are stiffer and have wider segments than the submerged leaves on the same plant.
  • Stem rather stout, mat-forming, branched or unbranched, 20"-100" long; lower and middle nodes mostly less than 3/8" apart
  • Turions yellow-green, present fall to early spring
  • Roots white, unbranched, and thread-like. Not always present.
  • Flowers yellow, in clusters of 3-6 in axils of modified leaves on an emergent spike, 1½"-4½" long. Flowers occasionally perfect but typically imperfect, the male and female flowers borne separately but on the same plant, the male borne above the female. Floral bracts much smaller than the leaves, mostly exceeding the flowers, palmately 7-lobed.
    • Sepals 4, green, united below, up to 1/16" long.
    • Petals 4, in the male flowers, united below, greenish, up to 1/16" long, absent in the female flowers.
    • Stamens 8
    • Pistil of 4 stigmas
    • Ovary inferior (below flower)
  • Fruit brownish, spherical, to 1/8" in diameter, the mericarps rounded on the back, smooth or somewhat roughened.
  • Seed

Identification:

  • A submerged aquatic plant, identifiable as a milfoil by its finely dissected, thread-like leaves.
  • Distinguished from other native milfoils by:
    • leaves in whorls
    • flowers borne in leaf axils
  • Quite similar to Common Water Milfoil (Myriophyllum sibericum) but typically larger and more robust, but with lower and middle nodes usually less than 3/8" (1cm) apart.

Distribution:

  • Circumboreal; in North America south to Massachusetts, New York, Indiana, NE Texas, Nebraska, Utah and British Columbia.
  • Also Eurasia.

Habitat:

  • Quiet waters of lakes, ponds, streams, and deep marshes, or rooting on muddy shores.

Associates:

  • Birds: The fruits are eaten by waterfowl.

History:

Uses:

Reproduction:

  • Sexually by seed (uncommon)
    • Flowering: June-September
  • Assexually by budding (most common)

Propagation:

  • By division

Cultivation:

  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Useful as oxygenator in garden ponds, and as shelter for small fishes and aquatic invertebrates.

Links:

Comments:

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Last updated on 26 February, 2004