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Native Plant Trust: Go Botany Discover thousands of New England plants

Lemna minor — common duckweed

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Facts

Among the smallest of all flowering plants, common duckweed is a free-floating aquatic perennial that forms a floating mat of minute foliage on the water surface. Common duckweed can be used to remove excess nutrients or toxic metals from water bodies (called phytoremediation) because it is an efficient bio-accumulator, is fast-growing and hardy, and is easily removed from the water after use.

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
  • Rhode Island
  • Vermont
Roots
there is approximately one root per thallus
Thallus shape in cross-section
the thallus is somewhat flattened on at least one side in cross-section
Thallus length
1–8 mm
Thallus shape
the thallus is ovate (egg-shaped)
Thallus dimensions
1.3–2
Veins on upper surface
3–5
Show all characteristics

  • Flowers

    Scale surrounding flower
    yes
    Stamen number
    2

  • Fruits or seeds

    Fruit length
    0.8–1 mm
    Seed surface ribbed
    the seed surface has ribs running from end to end

  • Growth form

    Root length
    Up to 150 mm
    Root number
    1
    Root sheath winged at base
    no
    Roots
    there is approximately one root per thallus
    Roots perforating basal scale
    there is no basal scale on the plant
    Thallus dimensions
    1.3–2
    Thallus edge
    the edge of the thallus is smooth (without teeth) near the tip
    Thallus length
    1–8 mm
    Thallus shape
    the thallus is ovate (egg-shaped)
    Thallus shape in cross-section
    the thallus is somewhat flattened on at least one side in cross-section
    Thallus stalks
    the thallus does not have a stalk
    Thallus width
    0.5–6.2 mm
    Thallus with red pigment
    yes
    Turions
    no

  • Leaves

    Papilla on thallus
    no
    Veins on upper surface
    3–5

  • Place

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

Wetland status

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

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
present

Conservation status

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

Massachusetts
widespread (S-rank: S5)

From Flora Novae Angliae dichotomous key

1.  Lemna minor L. N

common duckweed. Lemna minima Chev. ex Schleid. • CT, MA, ME, NH, RI, VT; throughout. Mesotrophic to eutrophic waters of lakes, rivers, beaver flowages, and pools.

Native to North America?

Yes

Sometimes confused with

Lemna turionifera:
small, rootless turions 0.8-1.6 mm in diameter sometimes produced and parent plants with red to purple coloration on lower surface (vs. L. minor, with turions never produced and parent plants usually green on lower surface).
Lemna perpusilla:
root sheath winged at base, roots up to 3.5 cm long, usually sharply pointed at apex, and thalli without anthocyanic pigment (vs. L. minor, with the root sheath not winged at base, roots to 15 cm long, frequently longer than 3.5 cm, rounded at apex, and thalli often with at least some spotting or diffuse coloring with anthocyanic pigment).

Synonyms

  • Lemna minima Chev. ex Schleid.

Family

Araceae

Genus

Lemna