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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

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North America distribution

Adapted from BONAP data

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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
Show all characteristics

  • 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
widespread (S-rank: S5)

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

Sometimes confused with

Potamogeton richardsonii:
leaf blades narrow-ovate to narrow-lanceolate, mostly 30–130 mm long, coarsely 13- to 21-veined, and stipules disintegrating into persistent fibers (vs. P. perfoliatus, with leaf blades ovate to suborbicular, mostly 9–76 mm long, delicately 7- to 15-veined, and stipules disintegrating and absent on the lower part of the stem).

Synonyms

  • Potamogeton amplexicaulis Kar.
  • Potamogeton bupleuroides Fern.
  • Potamogeton perfoliatus var. bupleuroides (Fern.) Farw.

Family

Potamogetonaceae

Genus

Potamogeton