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• Dichotomous Key
• Haloragaceae
• Myriophyllum
• Myriophyllum alterniflorum

Myriophyllum alterniflorum — alternate-flowered water-milfoil

Facts

Alternate-flowered water-milfoil has a circumboreal distribution, and in North America is found mainly in Canada and some northeastern states. In New England it can be found in all states but is most common in Maine, in still or slow-moving water of lakes and rivers. It is rare and protected in the southern New England states.

Habitat

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

Characteristics

• Clonal plantlets

  Turion length

  0 mm

• Flowers

  Anther length

  2 mm

  Carpels fused

  the carpels are fused to one another

  Flower lower lip length

  0 mm

  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

  20–50 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

  • red
  • yellow

  Petal length

  2–2.5 mm

  Petal number

  0–4

  Petal or sepal number

  there are four petals, sepals, or tepals in the flower

  Pistil number

  1

  Sepal appearance

  the sepals resemble leaves in color and texture

  Sepal length

  0.3–1 mm

  Sepal number

  4

  Sepals fused only to sepals

  the sepals are fused to each other (not other flower parts), at least near their bases

  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

  1.5–2 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)

• 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

  there are no turions on the plant

  Underground organs

  the plant has a rhizome (a horizontal underground stem with roots growing from it)

• 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

  Floral bract length

  1–2 mm

  Leaf arrangement

  whorled: there are three or more leaves per node along the stem

  Leaf blade length

  3–22 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 blade width

  3–14 mm

  Leaf position

  the leaves are all submerged underwater

  Leaf special features

  none of the mentioned special features are present

  Leaf-like branch segments

  6–18

  Leaf-like branch shape

  the leaf-like branches are round

  Specific leaf type

  the leaf is pinnately compound (i.e., it has three or leaflets distributed along a central axis

  Staminate bract edge (Myriophyllum)

  • the edges of the staminate bracts are either smooth and without teeth, or with tiny, outward-pointing teeth
  • the edges of the staminate bracts have either forward-pointing teeth, or are pinnately lobed (with lobes projecting from both sides of the central axis of the leaf)

  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 lanceolate (lance-shaped; widest below the middle and tapering at both ends)

  Underwater leaf blade width

  3–14 mm

  Underwater leaf length

  3–12 mm

  Underwater leaf stalk

  yes

  Underwater leaf stalk length

  0–2 mm

  Veins in floating leaf

  0

• Place

  Habitat

  aquatic

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • 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)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae