Lemna minuta — least duckweed
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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
Least duckweed is a tiny aquatic plant that reaches the northern edge of its rather patchy (disjunct) range on Martha's Vineyard Island in Massachusetts. To tell this species from other duckweeds, look closely at the "leaves" (thalli) with a hand lens. They will have a single vein that only extends about 2/3 of the length of the thallus. They will be solitary or paired (not form clusters), and their bases are symmetrical.
Habitat
Lacustrine (in lakes or ponds)
Characteristics
- Habitat
- aquatic
- New England state
- Massachusetts
- 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
- 0.8–4 mm
- Thallus shape
- the thallus is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
- Thallus dimensions
- 1–2
- Veins on upper surface
- 1
-
Flowers
- Scale surrounding flower
- no
- Stamen number
- 2
-
Fruits or seeds
- Fruit length
- 0.6–1 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
- 1–2
- Thallus edge
- the edge of the thallus is smooth (without teeth) near the tip
- Thallus length
- 0.8–4 mm
- Thallus shape
- the thallus is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
- 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
- Massachusetts
- Specific habitat
- in lakes or ponds
Wetland status
Occurs only in wetlands. (Wetland indicator code: OBL)
New England distribution and conservation status
Distribution
- Connecticut
- absent
- Maine
- absent
- Massachusetts
- present
- New Hampshire
- absent
- Rhode Island
- absent
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- not applicable (S-rank: SNA)
Native to North America?
Yes
Sometimes confused with
- Lemna valdiviana:
- 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 (vs. L. minuta, with the 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 ).
Synonyms
- Lemna minima Phil. ex Hegelm.
- Lemna minuscula Herter
- Lemna valdiviana Phil. var. minima Hegelm.
Family
Genus
From the dichotomous key of Flora Novae Angliae
2. Lemna minuta Kunth E
least duckweed. Lemna minima Phil. ex Hegelm.; L. minuscula Herter; L. valdiviana Phil. var. minima Hegelm. • MA. Pools. Lemna minuta growing in shade often has slightly longer thalli that are more transparent than those growing in sun. Further, shade-grown plants sometimes grow in connected clusters of up to four plants, making shade grown plants much harder to differentiate from L. valdiviana. Relative nerve length is one of the most important characters and appears to be stable (i.e., not environmentally controlled).