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Najas minor — brittle waternymph

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Facts

Brittle waternymph is an introduced species originating in Eurasia, and now occupying most of the Eastern United States. In New England it is mainly found in the western regions of Massachusetts, New Hampshire and Vermont, in non-acidic lakes and rivers. It is considered a potentially noxious weed and is banned from most New England states.

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
opposite: there are two leaves per node along the stem
Leaf blade length
5–34 mm
Petal or sepal number
there are no petals, sepals, or tepals in the flower, or they are not clearly present
Petal color
NA
Specific leaf type
the leaf is not divided, rather the blade is made up of one segment
Floating leaf shape
NA
Underwater leaf blade width
0.1–1.2 mm
Fruit type (general)
the fruit is dry and splits open when ripe
Underwater leaf length
5–34 mm
Show all characteristics

  • Clonal plantlets

    Turion length
    0 mm

  • Flowers

    Anther length
    0.3 mm
    Carpels fused
    NA
    Flower lower lip length
    0 mm
    Flower number
    1–2
    Flower position
    the flowers are below 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
    1.9–2.2 mm
    Inflorescence type
    • the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
    • the inflorescence has only one flower on it
    • the inflorescence is a monochasial cyme (an axis with a terminal flower, below it a branch with a terminal flower, this branch may itself have a branch and so on)
    Length of flower stalk
    At least 0 mm
    Length of peduncle
    At least 0 mm
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    1
    Ovary position
    the sepals and/or petals are attached above the ovary
    Palate on corolla
    NA
    Petal and sepal arrangement
    the flower includes neither petals nor sepals
    Petal appearance
    NA
    Petal color
    NA
    Petal fringed edges
    NA
    Petal fusion
    NA
    Petal hairs on inner/upper surface
    NA
    Petal length
    0 mm
    Petal number
    0
    Petal or sepal number
    there are no petals, sepals, or tepals in the flower, or they are not clearly present
    Pistil number
    1
    Sepal appearance
    NA
    Sepal length
    0 mm
    Sepal number
    0
    Sepals fused only to sepals
    NA
    Spur length
    0 mm
    Stamen number
    1 or 2
    Stamen position relative to petals
    NA
    Stamens fused
    • NA
    • the stamens are not fused to one another
    Stamens fused to petals
    the stamens are not fused to the petals or tepals
    Style length
    1–1.7 mm
    Style number
    1

  • Fruits or seeds

    Fruit length
    2–3 mm
    Fruit type (general)
    the fruit is dry and splits open when ripe
    Fruit type (specific)
    the fruit is an achene (dry, usually 1-seeded, does not separate or split open at maturity)

  • 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 only a single year or less
    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
    there are only slender roots on the plant

  • Leaves

    Bract position (Sparganium)
    NA
    Bract relative length
    At least 3854 mm
    Bracts
    neither the flowers nor their pedicels have bracts
    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
    NA
    Floral bract length
    0 mm
    Leaf arrangement
    opposite: there are two leaves per node along the stem
    Leaf blade length
    5–34 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
    0.1–1.2 mm
    Leaf position
    the leaves are all submerged underwater
    Leaf special features
    none of the mentioned special features are present
    Leaf-like branch segments
    0
    Leaf-like branch shape
    NA
    Specific leaf type
    the leaf is not divided, rather the blade is made up of one segment
    Staminate bract edge (Myriophyllum)
    NA
    Stipule appearance
    the stipules are firm or fibrous, and colored white, green or brown
    Stipule fused to leaf
    the stipules are attached to the leaf blade for some part of their length
    Stipules
    the plant has stipules
    Trap-bladder length
    0 mm
    Underwater leaf blade edges
    the underwater leaf blade edges are toothed
    Underwater leaf blade shape
    the underwater leaf blade is linear (very narrow with more or less parallel sides)
    Underwater leaf blade veins
    1
    Underwater leaf blade width
    0.1–1.2 mm
    Underwater leaf length
    5–34 mm
    Underwater leaf stalk
    no
    Underwater leaf stalk length
    0 mm
    Underwater leaf tip shape
    the tip of the underwater leaf is acute (sharply pointed)
    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 trails along the substrate, or floats in the water

Wetland status

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

In New England

Distribution

Connecticut
present, invasive, prohibited
Maine
present, invasive, prohibited
Massachusetts
present, invasive, prohibited
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.

Massachusetts
not applicable (S-rank: SNA)

From Flora Novae Angliae dichotomous key

4.  Najas minor All. E

brittle waternymph. Caulinia minor (All.) Coss. & Germ. • CT, MA, ME, NH, VT; primarily western portion of states. Still or slow-moving, circumneutral to basic water of lakes and rivers.

Native to North America?

No

Sometimes confused with

Najas flexilis:
each margin of the leaf blade with 35–80 minute, unicellular spinules and apex of leaf sheath convexly tapering into base of blade (vs. N. minor, with each margin of the leaf blade with 7–15 multicellular spinules and apex of leaf sheath truncate or auriculate).
Najas gracillima:
with the axis of seeds straight and leaf blades ascending to spreading, the margins with minute, unicellular teeth that usually require magnification to resolve (vs. N. minor, axis of seeds curved and leaf blades usually recurved in age, the margins with multicellular teeth that are often visible to the unaided eye).

Synonyms

  • Caulinia minor (All.) Coss. & Germ.

Family

Hydrocharitaceae

Genus

Najas