Myriophyllum sibiricum

Common Water Milfoil

Common Water Milfoil
Photo courtesy Wisconsin State Herbarium
and Robert W. Freckmann

Flora, fauna, earth, and sky...
The natural history of the northwoods

Name:

• Myriophyllum, from the Greek, murios (myrios), "countless, infinite", and fullon (phyllon), "leaf; foliage"; hence "many leaved"
• sibiricum, from the Latin, "of Siberia"
• Common name from its wide distribution (Originally given the scientific name of "Siberian Milfoil", it is widespread in North America as well.)
• Other common names include: American Milfoil, American Water Milfoil, Siberian Water Milfoil, Shortspike Water Milfoil, Whitish Water-Milfoil, Grønlandsk Tusindblad (Dan), Kalvaärviä (Fin), Myriophylle Blanchissant (Fr), Kamtusenblad (Nor), Knoppslinga, Kotteslinga (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: 503906
• Also known as Myriophyllum exalbescens, Myriophyllum exalbescens var. magdalenense, Myriophyllum magdalenense, Myriophyllum spicatum var. capillaceum, Myriophyllum spicatum var. exalbescens, Myriophyllum spicatum var. squamosum, Myriophyllum spicatum ssp. exalbescens, Myriophyllum spicatum ssp. squamosum

Description:

• A free floating, submerged, perennial aquatic herb
• Leaves in whorls of 3-4; ½"-1½" long, pinnately dissected, with 5-10 thread-like segments on each side of midrib; internodes between whorls about 3/8" long.
• Stem simple to freely branched, elongate and flexuous, to 3'-5' long
• Turions with reduced blackish leaves and shortened internodes often produced from lower nodes in late summer and fall, present through spring.
• Roots white, thread-like; not always present
  • Flowers imperfect, borne in whorls on red spikes raised above the water's surface, the male flowers above the female. Floral spikes 1½"-4" long; clearly differentiated from underwater stems; floral bracts on spike much smaller than leaves, oblong to obovate in form.
  • Petals pink on male flower; absent on female, oblong-obovate, concave, 2mm-3 mm long
  • Stamens 8, yellow-green anthers conspicouous when flowering
  • Pistil of 4 chambers
  • Ovary superior (within blossom)
• Fruit olive, more-or-less round, 2-4mm long, the segments rounded on back
• Seed

Identification:

• A submerged aquatic plant, identifiable as a milfoil by its finely dissected, thread-like leaves.
• Distinguished from other native milfoils by:
  • leaves and flowers in whorls
  • bracts surrounding male flowers entire and not longer than the flowers.
• Distinguished from the evil invader, Eurasian Water Milfoil (Myriophyllum spicatum), which it closely resembles, by its less finely divided leaves and larger floral bracts. Our native Common Milfoil typically has 5-10 thread-like segments on each side of the midrib; its Eurasian cousin is more finely divided, with 12-24 segments.
• Plants often turn whitish when dried.

Distribution:

• Boreal North America, south to Maryland, Ohio, Indiana, Texas, New Mexico, and California.
• Eurasia

Habitat:

• Shallow to deep water of lakes, ponds, marshes, ditches and sluggish streams; common and often abundant, the numerous reddish spikes often conspicuous on the water surface.
• Its presence significantly increases the abundance of most groups of macroinvertebrates, including gastropods, amphipods, daphnids, chironomids, ephemeropterans, trichopterans, and odonates - though not so much the copepods and oligochaetes. The value of milfoil to macroinvertebrates is likely due more to its value as habitat than as food.
• The Eurasian Water Milfoil (Myriophyllum spicatum) is introduced and spreading in eastern US. The more aggressive nature of Eurasian milfoil makes it a potential menace in recreational waters. Extreme care should be exercised when boating or fishing in infested waters so as not to inadvertently introduce the plant to uninfested lakes and streams.

Associates:

History:

Uses:

Reproduction:

• Sexually by seed (uncommon)
  • Flowers 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:

• Den Virtuella Floren, Naturhistoriska riksmuseet, Stockholm

Comments: