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- Potamogetonaceae
- Potamogeton
- Potamogeton perfoliatus
Potamogeton perfoliatus — clasping-leaved pondweed
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Facts
Clasping-leaved pondweed has a circumboreal distribution and is also found in Africa, Australia and Central America. However, in North America it is essentially confined to the Northeast. As the name suggests, the leaf blade clasps the stem in this submerged species lacking floating leaves. Clasping-leaved pondweed was one of the prominent aquatic species in the Chesapeake Bay before it began to decline in the 1960s and 1970s.
Habitat
Lacustrine (in lakes or ponds), riverine (in rivers or streams), shores of rivers or lakes
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
- wetlands
- 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
- 9–97 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
- NA
- Underwater leaf blade width
- 7–40 mm
- Fruit type (general)
-
- the fruit is dry but does not split open when ripe
- the fruit is fleshy
- Underwater leaf length
- 9–97 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
- 4–48 mm
- Inflorescence type
- the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
- Inflorescence width
- 8 mm
- Length of flower stalk
- 0 mm
- Length of peduncle
- 10–135 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 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
- 0.4–0.6 mm
- Fruit length
- 1.6–3 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
- 1.3–2.2 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
- 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
- 9–97 mm
- Leaf blade veins
- the lateral veins are parallel or slightly arched in the direction of the tip
- Leaf blade width
- 7–40 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 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 1439
- Underwater leaf air passage relative width
- At least 4336
- Underwater leaf air passage row number
- 0
- Underwater leaf blade edges
- the underwater leaf has tiny, one-celled spines or points along the edge
- Underwater leaf blade shape
-
- the underwater leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
- the underwater leaf blade is orbicular (roughly circular, as wide as long)
- the underwater leaf blade is ovate (widest below the middle and broadly tapering at both ends)
- Underwater leaf blade veins
- 7–15
- Underwater leaf blade width
- 7–40 mm
- Underwater leaf length
- 9–97 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
- 0
-
Place
- Habitat
-
- aquatic
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- in lakes or ponds
- in rivers or streams
- shores of rivers or lakes
-
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
- unranked (S-rank: SNR)
From Flora Novae Angliae dichotomous key
19. Potamogeton perfoliatus L. N
clasping-leaved pondweed. Potamogeton amplexicaulis Kar.; P. bupleuroides Fern.; P. perfoliatus L. var. bupleuroides (Fern.) Farw. • CT, MA, ME, NH, RI, VT; throughout. Shallow, still or slow-moving, circumneutral to basic water of lakes and rivers, sometimes periodically stranded on mud along tidal rivers.
1×19. Potamogeton alpinus × Potamogeton perfoliatus → Potamogeton ×prussicus Hagstr. is a very rare pondweed hybrid known from VT. It is intermediate in morphology between the parental species.
3×19. Potamogeton berchtoldii × Potamogeton perfoliatus → Potamogeton ×mysticus Morong is a rare pondweed hybrid known from MA, ME, VT. It generally resembles P. gramineus, but the submersed blades vary from sessile to weakly clasping.
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).
11×19. Potamogeton gramineus × Potamogeton perfoliatus → Potamogeton ×nitens G. Weber is an uncommon pondweed hybrid known from CT, MA, ME, NH, VT. It ± resembles P. gramineus, but some of the leaf blades weakly clasp the stem. It is further characterized by submersed leaves 5–23 mm wide with 7–17 veins, floating leaves sometimes produced on mature plants that are 27–65 mm long and with 11–17 veins, and stipules 5–28 mm long. It is very similar to P. ×versicolor (7 ×19; see that nothospecies for discussion).
19×23. Potamogeton perfoliatus × Potamogeton richardsonii → Potamogeton ×absconditus Z. Kaplan, Fehrer, & Hellquist is a very rare pondweed hybrid known from CT, ME, VT. It is very difficult to distinguish from its parental taxa due to the close morphological similarity. It is most similar to P. perfoliatus with regard to habit and leaf blade shape, but the stipules, even though translucent and delicate, disintegrate into ± white fibers like P. richardsonii (but the fibers can be very fine and difficult to detect).
Native to North America?
Yes
Synonyms
- Potamogeton amplexicaulis Kar.
- Potamogeton bupleuroides Fern.
- Potamogeton perfoliatus var. bupleuroides (Fern.) Farw.