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- Potamogeton epihydrus
Potamogeton epihydrus — ribbon-leaved pondweed
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Facts
Ribbon-leaved pondweed is a common species throughout the northern United States and southern Canada, and it is found throughout New England. The submersed leaves are narrow and ribbon-like, thin and transparent, with prominent bands of lacunar cells 1–2 mm wide on each side of the midrib. The floating leaves are broad and elliptical.
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.
Characteristics
- Habitat
- aquatic
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Leaf position
-
- some of the leaves are floating at the surface of the water
- the leaves are all submerged underwater
- Leaf arrangement
- alternate: there is one leaf per node along the stem
- Leaf blade length
- 20–220 mm
- Petal or sepal number
- there are four petals, sepals, or tepals in the flower
- Petal color
- green
- Specific leaf type
- the leaf is not divided, rather the blade is made up of one segment
- Floating leaf shape
-
- the leaf blade is elliptic (widest near the middle and tapering at both ends)
- the leaf blade is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
- the leaf blade is oblong (rectangular but with rounded ends)
- Underwater leaf blade width
- 1–10 mm
- Fruit type (general)
-
- the fruit is dry but does not split open when ripe
- the fruit is fleshy
- Underwater leaf length
- 50–220 mm
-
Clonal plantlets
- Turion length
- 0 mm
-
Flowers
- Anther color
- there is a noticeable pink, reddish or purplish tint to the anthers
- 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
- 8–40 mm
- Inflorescence type
- the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
- Length of flower stalk
- 0 mm
- Length of peduncle
- 15–160 mm
- Nectar spur
- the flower has no nectar spurs
- Number of carpels
- 1–4
- 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
- green
- Petal fringed edges
- the petals are not fringed
- Petal fusion
- the perianth parts are separate
- Petal hairs on inner/upper surface
- there are no hairs on the inner/upper petal surface
- Petal length
- 1.5–3 mm
- Petal number
- 4
- Petal or sepal number
- there are four petals, sepals, or tepals in the flower
- Pistil number
-
- 1
- 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
- the stamens are not fused to one another
- Stamens fused to petals
- the stamens are fused near the bases of the petals or tepals
- Style number
- 0–4
-
Fruits or seeds
- Fruit beak length
- 0.5 mm
- Fruit length
- 2.5–4.5 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
- 2–3.6 mm
-
Glands or sap
- Oil glands on nodes
- none of the nodes have oil glands
- 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
- there are no turions on the plant
- 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
- no
- Floating leaf blade width
- 4–20 mm
- Floating leaf length
- 20–80 mm
- Floating leaf shape
-
- the leaf blade is elliptic (widest near the middle and tapering at both ends)
- the leaf blade is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
- the leaf blade is oblong (rectangular but with rounded ends)
- Floating leaf tip
- the tip of the floating leaf blade is rounded, with no point
- Floral bract form
- NA
- Floral bract length
- 0 mm
- Leaf arrangement
- alternate: there is one leaf per node along the stem
- Leaf blade length
- 20–220 mm
- Leaf blade veins
- the lateral veins are parallel or slightly arched in the direction of the tip
- Leaf blade width
- 1–20 mm
- Leaf position
-
- some of the leaves are floating at the surface of the water
- 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 firm or fibrous, and colored white, green or brown
- 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 form a completely 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 1442
- Underwater leaf air passage row number
- 9–18
- 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
- 3–13
- Underwater leaf blade width
- 1–10 mm
- Underwater leaf length
- 50–220 mm
- Underwater leaf stalk
- no
- Underwater leaf stalk length
- 0 mm
- Underwater leaf tip shape
-
- the tip of the underwater leaf is acute (sharply pointed)
- the tip of the underwater leaf is obtuse (bluntly pointed)
- the tip of the underwater leaf is rounded, with no point
- Veins in floating leaf
- 11–41
-
Place
- Habitat
- aquatic
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- in lakes or ponds
- in rivers or streams
-
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.
- Massachusetts
- widespread (S-rank: S5)
From Flora Novae Angliae dichotomous key
7. Potamogeton epihydrus Raf. N
ribbon-leaved pondweed. Potamogeton epihydrus Raf. var. nuttallii (Cham. & Schlecht.) Fern.; P. epihydrus Raf. var. ramosus (Peck) House • CT, MA, ME, NH, RI, VT; throughout. Shallow, still or slow-moving, acidic to basic water of lakes and rivers.
4×7. Potamogeton bicupulatus × Potamogeton epihydrus → Potamogeton ×aemulans Z. Kaplan, Hellquist, & Fehrer is a rare pondweed hybrid responsible for reports of Potamogeton diversifolius Raf. in New England. It has submersed leaves 0.2–1.8 mm wide that are 3 (–5)-veined, with or without a narrow band of lacunae bordering the midrib. The stipules are 3–34 mm long, mostly distinct from the leaf but some connate for a short distance (up to 2.8 mm). The floating leaves, which are always present on flowering plants, are 18–35 ×5–11 mm and have 9–15 veins. The hybrid shows dimorphic inflorescences (within a population), with some short ones (2–3 mm) in the axils of submerged leaves and longer ones (3–6 mm) in emersed spikes. This hybrid is known from CT, MA, and is found primarily in slow-moving, circumneutral water of rivers.
7×19. Potamogeton epihydrus × Potamogeton perfoliatus → Potamogeton ×versicolor Z. Kaplan, Hellquist, & Fehrer is a rare pondweed known from ME. It ± resembles Potamogeton alpinus, but the submersed blades have prominent lacunar bands, and the narrow-lanceolate blades sometimes have weakly clasping bases. Floating leaves are sometimes produced on mature plants and have short petioles 4–22 mm long (compared with 20–125 mm in P. epihydrus). This hybrid closely resembles P. ×nitens ( P. gramineus ×P. perfoliatus) but has submersed leaves 4–11 mm wide and floating leaves 22–32 mm long with apically winged petioles 4–22 mm long (vs. submersed leaves 5–23 mm and floating leaves 27–65 mm with apically unwinged or barely winged petioles 12–40 mm long).
Native to North America?
Yes
Sometimes confused with
- Potamogeton zosteriformis:
- floating leaves always absent and submersed leaves with 15-25 veins, lacking lacunae (vs. P. epihydrus, with floating leaves usually produced on some plants and submersed leaves with 3-13 veins, with prominent bands of lacunae on each side of the midrib).
Synonyms
- Potamogeton epihydrus var. nuttallii (Cham. & Schlecht.) Fern.
- Potamogeton epihydrus var. ramosus (Peck) House