Lemna valdiviana — pale duckweed
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Facts
Although Pale duckweed is a widespread native species found in several New England states, it is considered endangered in New Hampshire. The "leaves" (thalli) of this aquatic plant have a prominent midvein that extends nearly the length of the leaf, and their bases are asymmetrical.
Habitat
Lacustrine (in lakes or ponds), riverine (in rivers or streams)
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.
Found this plant? Take a photo and post a sighting.
enlargeCharacteristics
- Habitat
- aquatic
- New England state
-
- Connecticut
- Massachusetts
- New Hampshire
- Rhode Island
- 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
- 1–5 mm
- Thallus shape
-
- the thallus is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
- the thallus is ovate (egg-shaped)
- Thallus dimensions
- 1.3–3
- Veins on upper surface
- 1
-
Flowers
- Scale surrounding flower
- no
- Stamen number
- 2
-
Fruits or seeds
- Fruit length
- 1–1.35 mm
- Seed surface ribbed
- the seed surface has ribs running from end to end
-
Growth form
- Root length
- Up to 15 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
- 1.3–3
- Thallus edge
- the edge of the thallus is smooth (without teeth) near the tip
- Thallus length
- 1–5 mm
- Thallus shape
-
- the thallus is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
- 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 has a stalk
- Thallus with red pigment
- no
- Turions
- no
-
Leaves
- Papilla on thallus
-
- no
- yes
- Veins on upper surface
- 1
-
Place
- Habitat
- aquatic
- New England state
-
- Connecticut
- Massachusetts
- New Hampshire
- Rhode Island
- 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
- absent
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- present
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Connecticut
- unrankable (S-rank: SU)
- Massachusetts
- historical (S-rank: SH), H (code: H)
- New Hampshire
- historical (S-rank: SH), endangered (code: E)
- Rhode Island
- extremely rare (S-rank: S1), concern (uncertain) (code: C*)
From Flora Novae Angliae dichotomous key
6. Lemna valdiviana Phil. NC
pale duckweed. Lemna torreyi Austin • CT, MA, NH, RI. Mesotrophic to eutrophic waters of lakes, rivers, beaver flowages, and pools.
Native to North America?
Yes
Sometimes confused with
- Lemna minuta:
- vein usually not extending past aerenchyma tissue, extending less than 2/3 of distance from root node to tip of thallus, thalli mostly 1–2.5 mm long, 1–2 times as long as broad, broad-elliptic to broad-oblong or obovate (vs. L. valdiviana, with the vein usually extending past aerenchyma tissue, extending at least 3/4 of the distance from the root node to the tip of the thallus, and thalli 2–4 mm long, 1.3–3 times as long as wide, elliptic to lanceolate or obovate).
Synonyms
- Lemna torreyi Austin