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Myriophyllum sibiricum — northern water-milfoil

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Facts

The native northern water-milfoil is often difficult to separate from the invasive Eurasian water-milfoil, whose leaves have more dissections. Northern water-milfoil was used by the Iroquois to treat poor blood circulation in adolescents.

Habitat

Lacustrine (in lakes or ponds), riverine (in rivers or streams)

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
aquatic
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont
Leaf position
the leaves are all submerged underwater
Leaf arrangement
whorled: there are three or more leaves per node along the stem
Leaf blade length
10–50 mm
Petal or sepal number
  • there are four petals, sepals, or tepals in the flower
  • there are no petals, sepals, or tepals in the flower, or they are not clearly present
Petal color
pink
Specific leaf type
the leaf is once pinnately divided and the segments are very narrow, each side providing the appearance of a comb
Floating leaf shape
NA
Fruit type (general)
the fruit is dry and splits open when ripe
Underwater leaf length
10–50 mm
Show all characteristics

  • Clonal plantlets

    Turion length
    At least 20 mm

  • Flowers

    Anther color
    there is a noticeable pink, reddish or purplish tint to the anthers
    Carpels fused
    the carpels are fused to one another
    Flower lower lip length
    0 mm
    Flower number
    2–4
    Flower position
    the flowers are above the surface of the water
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Inflorescence length
    40–100 mm
    Inflorescence type
    the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
    Length of flower stalk
    0 mm
    Length of peduncle
    0 mm
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    4
    Ovary position
    the sepals and/or petals are attached above the ovary
    Palate on corolla
    no
    Petal and sepal arrangement
    the flower includes two cycles of petal- or sepal-like structures
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal color
    pink
    Petal length
    2.5 mm
    Petal number
    0–4
    Petal or sepal number
    • there are four petals, sepals, or tepals in the flower
    • there are no petals, sepals, or tepals in the flower, or they are not clearly present
    Pistil number
    1
    Sepal appearance
    the sepals resemble leaves in color and texture
    Sepal length
    Up to 5 mm
    Sepal number
    0–4
    Spur length
    0 mm
    Stamen length
    1.2–2 mm
    Stamen number
    8
    Stamen position relative to petals
    NA
    Stamens fused to petals
    the stamens are not fused to the petals or tepals
    Style length
    0 mm
    Style number
    0

  • Fruits or seeds

    Fruit length
    2.3–3 mm
    Fruit type (general)
    the fruit is dry and splits open when ripe
    Fruit type (specific)
    the fruit is a schizocarp (when dry it splits into sections, each holding one or more seeds)
    Fruit width
    Up to 3 mm

  • Glands or sap

    Oil glands on nodes
    none of the nodes have oil glands
    Sap
    the sap is clear and watery

  • Growth form

    Lifespan
    the plant lives more than two years
    Root septa
    the roots do not have transverse septa
    Roots floating in water
    there are no clusters of roots floating in the water
    Turions
    the plant has turions
    Underground organs
    • the plant has a rhizome (a horizontal underground stem with roots growing from it)
    • there are only slender roots on the plant

  • Leaves

    Bract position (Sparganium)
    NA
    Bract relative length
    At least 1379 mm
    Bracts
    the flowers or their pedicels have bracts at their bases
    Floating leaf basal lobes
    NA
    Floating leaf blade width
    0 mm
    Floating leaf length
    0 mm
    Floating leaf shape
    NA
    Floating leaf tip
    NA
    Floral bract form
    the bracts are much more lobed, or much less lobed, than the foliage leaves
    Leaf arrangement
    whorled: there are three or more leaves per node along the stem
    Leaf blade length
    10–50 mm
    Leaf blade veins
    the lateral veins radiate from the base and continue to spread away from the centerline of the leaf, or branch off the central vein at intervals
    Leaf position
    the leaves are all submerged underwater
    Leaf special features
    none of the mentioned special features are present
    Leaf-like branch segments
    5–12
    Leaf-like branch shape
    the leaf-like branches are round
    Specific leaf type
    the leaf is once pinnately divided and the segments are very narrow, each side providing the appearance of a comb
    Staminate bract edge (Myriophyllum)
    the edges of the staminate bracts are either smooth and without teeth, or with tiny, outward-pointing teeth
    Stipule appearance
    NA
    Stipule fused to leaf
    NA
    Stipules
    there are no stipules on the plant
    Stipules fused around stem
    NA
    Trap-bladder length
    0 mm
    Underwater leaf blade edges
    the underwater leaf blades are lobed
    Underwater leaf blade shape
    • the underwater leaf blade is oblong (rectangular but with rounded ends)
    • the underwater leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    Underwater leaf length
    10–50 mm
    Underwater leaf stalk
    yes
    Underwater leaf stalk length
    0–2 mm
    Underwater leaf tip shape
    the tip of the underwater leaf is rounded, with no point
    Veins in floating leaf
    0

  • Place

    Habitat
    aquatic
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Vermont
    Specific habitat
    • in lakes or ponds
    • in rivers or streams

  • Stem, shoot, branch

    Flowering stem growth form
    the flowering stem is upright

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present, invasive, prohibited
Rhode Island
absent
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Connecticut
extremely rare (S-rank: S1), threatened (code: T)
Massachusetts
extremely rare to rare (S-rank: S1S2)
New Hampshire
unrankable (S-rank: SU), Ind (code: Ind)

From Flora Novae Angliae dichotomous key

7.  Myriophyllum sibiricum Komarov N

northern water-milfoil. Myriophyllum exalbescens Fern.; M. spicatum L. ssp. exalbescens (Fern.) Hultén; M. spicatum L. var. exalbescens (Fern.) Jepson • CT, MA, ME, NH, VT; reported from RI by George (1992), but specimens are unknown. Slow or still-moving, circumneutral to basic water of lakes and rivers. This native species is sometimes difficult to separate from the introduced Myriophyllum spicatum. In addition to characters used in the key, M. sibiricum has knob-like vegetative shoot apices and stems that usually become distinctly whitened in drying, while 
 M. spicatum has tassel-like vegetative shoot apices and stems that remain green or brown (rarely whitening) in drying.

Native to North America?

Yes

Sometimes confused with

Myriophyllum spicatum:
middle leaves with mostly 12–20 segments on each side of the rachis, uppermost leaves truncate at the apex, stems thicker below the inflorescence than at the stem base, up to twice as thick, and turions not formed (vs. M. sibiricum, with the middle leaves with mostly 6–12 segments on each side of the rachis, upper leaves rounded at the apex, stems of +/- similar diameter below the inflorescence and near the stem base, and turions formed in the fall).
Myriophyllum alterniflorum:
with flowers and their subtending bracts alternate, sometimes the lowest opposite, leaf blades with usually 3–7 pairs of narrow segments, and turions not formed (vs. M. sibiricum, flowers and their subtending bracts whorled, leaf blades with usually 6–12 pairs of narrow segments, and turions formed in late season).

Synonyms

  • Myriophyllum exalbescens Fern.
  • Myriophyllum spicatum L. ssp. exalbescens (Fern.) Hultén
  • Myriophyllum spicatum L. var. exalbescens (Fern.) Jepson

Family

Haloragaceae

Genus

Myriophyllum