Wolffia borealis — northern water-meal
![Plant form: Wolffia borealis. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Araceae/wolffia-borealis-ha-ahaines.jpg)
![Plant form: Wolffia borealis. ~ By Andrew Nelson. ~ Copyright © 2024 Andrew Nelson. ~ andrew.nelson[at]oswego.edu ~ Flora of Rice Creek Field Station - www.oswego.edu/academics/opportunities/rice_creek_field_station](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Araceae/wolffia-borealis-ha-anelson2.jpg)
![Thalli: Wolffia borealis. ~ By Gordon Morrison. ~ Copyright © 2024 New England Wild Flower Society. ~ Image Request, images[at]newenglandwild.org](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Araceae/wolffia-borealis-ta-gmorrison.jpg)
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New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
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enlargeFacts
Northern water-meal is absent from much of northern New England, except in Vermont's Champlain Valley. Water-meal (Wolffia) species have no roots. In a study comparing northern water-meal with common duckweed (Lemna minor) and common duck-meal (Spirodela polyrrhiza), northern water-meal had the fastest rate of production (0.62 fronds per day).
Habitat
Lacustrine (in lakes or ponds), riverine (in rivers or streams)
Characteristics
- Habitat
- aquatic
- New England state
-
- Maine
- Massachusetts
- New Hampshire
- Vermont
- Roots
- there are no roots on the plant
- Thallus shape in cross-section
- the thallus is somewhat flattened on at least one side in cross-section
- Thallus length
- 0.7–1.5 mm
- Thallus shape
- the thallus is another shape in outline
- Thallus dimensions
- 1.3–2
- Veins on upper surface
- 0
-
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
- 1.3–2
- Thallus edge
- the edge of the thallus is smooth (without teeth) near the tip
- Thallus length
- 0.7–1.5 mm
- Thallus shape
- the thallus is another shape in outline
- 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
- 0.4–1.2 mm
- Thallus with red pigment
- no
- Turions
- yes
-
Leaves
- Papilla on thallus
- no
- Veins on upper surface
- 0
-
Place
- Habitat
- aquatic
- New England state
-
- 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)
New England distribution and conservation status
Distribution
- Connecticut
- absent
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- absent
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- unranked (S-rank: SNR)
Native to North America?
Yes
Sometimes confused with
- Wolffia columbiana:
- plants spherical to ovoid, not flattened on the upper surface, without any upward bent points (vs. W. borealis, with plants flattened on top and with an upward bent point at each end).
- Wolffia brasiliensis:
- thalli rounded at each apex, with a large, prominent papilla in the center of the upper surface, 1–1.5 times as long as wide (vs. W. borealis, with thalli with a minute, upward-bent point at each apex, lacking a central papilla, 1.3–2 times as long as wide).
Synonyms
- Wolffia brasiliensis Weddell var. borealis Engelm. ex Hegelm.
- Wolffia punctata, misapplied
Family
Genus
From the dichotomous key of Flora Novae Angliae
1. Wolffia borealis (Engelm. ex Hegelm.) Landolt ex Landolt & Wildi N
northern water-meal. Wolffia brasiliensis Weddell var. borealis Engelm. ex Hegelm.; W. punctata, auct. non Griseb. • MA, ME, NH, VT; also reported from CT by Landolt (2000), but specimens are unknown; extending north in the Lake Champlain Valley but absent over much of northern New England. Mesotrophic to eutrophic waters of lakes, rivers, and backwaters.