Potamogeton confervoides — alga-like pondweed, Tuckerman's pondweed
![Inflorescences: Potamogeton confervoides. ~ By Gordon Morrison. ~ Copyright © 2024 New England Wild Flower Society. ~ Image Request, images[at]newenglandwild.org](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Potamogetonaceae/potamogeton-confervoides-in-gmorrison.jpg)
![Flowers and fruits: Potamogeton confervoides. ~ By Jennifer Garrett. ~ Copyright © 2024 Jennifer Garrett. ~ gemmiferg[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Potamogetonaceae/potamogeton-confervoides-ff-jgarrett.jpg)
![Stems: Potamogeton confervoides. ~ By C. Barre Hellquist. ~ Copyright © 2024 C. Barre Hellquist. ~ C.Barre.Hellquist[at]mcla.edu ~ U. of New Hampshire](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Potamogetonaceae/potamogeton-confervoides-st-cbhellquist.jpg)
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Facts
Alga-like pondweed is found mostly in shallow waters of acidic lakes and ponds. It has extremely fine, flaccid leaves that look like green hairs underwater and collapse into one another when removed from the water.
Habitat
Lacustrine (in lakes or ponds)
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
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Leaf position
- the leaves are all submerged underwater
- Leaf arrangement
- alternate: there is one leaf per node along the stem
- Leaf blade length
- 18–65 mm
- Petal or sepal number
- there are four petals, sepals, or tepals in the flower
- Petal color
-
- brown
- green
- Specific leaf type
- the leaf is not divided, rather the blade is made up of one segment
- Floating leaf shape
- NA
- Underwater leaf blade width
- 0.1–0.5 mm
- Fruit type (general)
-
- the fruit is dry but does not split open when ripe
- the fruit is fleshy
- Underwater leaf length
- 18–65 mm
-
Clonal plantlets
- Turion length
- 7–20 mm
-
Flowers
- Carpels fused
- the carpel is solitary or (if 2 or more) the carpels are not fused to one another
- Flower lower lip length
- 0 mm
- Flower position
- the flowers are above the surface of the water
- Flower symmetry
- there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
- Inflorescence length
- 5–12 mm
- Inflorescence type
- the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
- Length of peduncle
- 30–250 mm
- Nectar spur
- the flower has no nectar spurs
- Number of carpels
- 4
- Ovary position
- the sepals and/or petals are attached below the ovary
- Palate on corolla
- no
- Petal and sepal arrangement
- the flower includes only one cycle of petals or sepals
- Petal appearance
- the petals are green and/or leafy in texture
- Petal color
-
- brown
- green
- Petal fringed edges
- the petals are not fringed
- Petal hairs on inner/upper surface
- there are no hairs on the inner/upper petal surface
- Petal number
- 4
- Petal or sepal number
- there are four petals, sepals, or tepals in the flower
- Pistil number
- 4
- Sepal appearance
- NA
- Sepal length
- 0 mm
- Sepal number
- 0
- Sepals fused only to sepals
- NA
- Spur length
- 0 mm
- Stamen number
- 4
- Stamen position relative to petals
- NA
- Stamens fused to petals
- the stamens are fused near the bases of the petals or tepals
- Style number
- 4
-
Fruits or seeds
- Fruit beak length
- 0.5 mm
- Fruit length
- 2–3 mm
- Fruit type (general)
-
- the fruit is dry but does not split open when ripe
- the fruit is fleshy
- Fruit type (specific)
-
- the fruit is a drupe (fleshy, with a firm inner ovary wall that encloses a single seed)
- the fruit is an achene (dry, usually 1-seeded, does not separate or split open at maturity)
- Fruit width
- 1.7–2.8 mm
-
Glands or sap
- Sap
- the sap is clear and watery
-
Growth form
- Lifespan
- the plant lives more than two years
- Root septa
- the roots do not have transverse septa
- Roots floating in water
- there are no clusters of roots floating in the water
- Turions
- the plant has turions
- Underground organs
- the plant has a rhizome (a horizontal underground stem with roots growing from it)
-
Leaves
- Bract position (Sparganium)
- NA
- Bract relative length
- At least 3854 mm
- Bracts
- neither the flowers nor their pedicels have bracts
- Floating leaf basal lobes
- NA
- Floating leaf blade width
- 0 mm
- Floating leaf length
- 0 mm
- Floating leaf shape
- NA
- Floating leaf tip
- NA
- Floral bract form
- NA
- Floral bract length
- 0 mm
- Leaf arrangement
- alternate: there is one leaf per node along the stem
- Leaf blade length
- 18–65 mm
- Leaf blade veins
- the lateral veins radiate from the base and continue to spread away from the centerline of the leaf, or branch off the central vein at intervals
- Leaf blade width
- 0.1–0.5 mm
- Leaf position
- the leaves are all submerged underwater
- Leaf special features
- none of the mentioned special features are present
- Leaf-like branch segments
- 0
- Leaf-like branch shape
- NA
- Specific leaf type
- the leaf is not divided, rather the blade is made up of one segment
- Staminate bract edge (Myriophyllum)
- NA
- Stipule appearance
- the stipules are delicate and translucent
- Stipule fused to leaf
- the stipules are not attached to the leaf blade at all
- Stipules
- the plant has stipules
- Stipules fused around stem
- the stipules do not forma closed tube around the stem
- Trap-bladder length
- 0 mm
- Underwater leaf air passage number
- At least 1440
- Underwater leaf air passage relative width
- At least 1441
- Underwater leaf blade edges
- the underwater leaf has smooth edges, without teeth
- Underwater leaf blade shape
- the underwater leaf blade is linear (very narrow with more or less parallel sides)
- Underwater leaf blade veins
- 1
- Underwater leaf blade width
- 0.1–0.5 mm
- Underwater leaf length
- 18–65 mm
- Underwater leaf stalk
- no
- Underwater leaf stalk length
- 0 mm
- Underwater leaf tip shape
- the tip of the underwater leaf is acuminate (tapers to a long, thin point)
- Veins in floating leaf
- 0
-
Place
- Habitat
- aquatic
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
- in lakes or ponds
-
Stem, shoot, branch
- Flowering stem growth form
- the flowering stem is upright
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.
- Connecticut
- extremely rare (S-rank: S1), endangered (code: E)
- Massachusetts
- rare (S-rank: S2), threatened (code: T)
- Rhode Island
- historical (S-rank: SH), state historical (code: SH)
- Vermont
- rare (S-rank: S2)
From Flora Novae Angliae dichotomous key
5. Potamogeton confervoides Reichenb. N
alga-like pondweed. CT, MA, ME, NH, RI, VT. Shallow acidic to, less commonly, circumneutral water of lakes and ponds, frequently occurring in north-temperate to boreal areas.
Native to North America?
Yes