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Wolffia columbiana — Columbian water-meal

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Facts

Columbian water-meal is generally considered to be the smallest flowering plant on earth, less than 1/16 inch (1.5 mm) long. It floats at the water surface in mesotrophic to eutrophic lakes, rivers and backwaters. It is widely distributed across North, Central and South America. But it is rare and sporadic in northern New England.

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
Roots
there are no roots on the plant
Thallus shape in cross-section
the thallus is rounded in cross-section
Thallus length
0.5–1.4 mm
Thallus shape
the thallus is orbicular (roughly circular, as wide as long)
Thallus dimensions
1–1.3
Veins on upper surface
0
Show all characteristics

  • Flowers

    Scale surrounding flower
    no
    Stamen number
    1

  • Fruits or seeds

    Seed surface ribbed
    the seed surface is nearly smooth

  • Growth form

    Root length
    0 mm
    Root number
    0
    Root sheath winged at base
    NA
    Roots
    there are no roots on the plant
    Roots perforating basal scale
    NA
    Thallus dimensions
    1–1.3
    Thallus edge
    the edge of the thallus is smooth (without teeth) near the tip
    Thallus length
    0.5–1.4 mm
    Thallus shape
    the thallus is orbicular (roughly circular, as wide as long)
    Thallus shape in cross-section
    the thallus is rounded in cross-section
    Thallus stalks
    the thallus does not have a stalk
    Thallus width
    0.4–1.2 mm
    Thallus with red pigment
    no
    Turions
    yes

  • Leaves

    Papilla on thallus
    no
    Veins on upper surface
    0

  • Place

    Habitat
    aquatic
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • 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.

Maine
rare (S-rank: S2), special concern (code: SC)
Massachusetts
fairly widespread (S-rank: S4)

From Flora Novae Angliae dichotomous key

3.  Wolffia columbiana Karst. N

Columbian water-meal. Bruniera columbiana (Karst.) Nieuwl. • CT, MA, ME, NH, VT; rare and sporadic in northern New England. Mesotrophic to eutrophic waters of lakes, rivers, and backwaters.

Native to North America?

Yes

Sometimes confused with

Wolffia borealis:
plants flattened on top and with an upward bent point at each end (vs. W. columbiana, which are plants spherical to ovoid, not flattened on the upper surface, without any upward bent points).

Synonyms

  • Bruniera columbiana (Karst.) Nieuwl.

Family

Araceae

Genus

Wolffia