Potamogeton strictifolius — straight-leaved pondweed
![Special features: Potamogeton strictifolius. ~ By Gordon Morrison. ~ Copyright © 2024 New England Wild Flower Society. ~ Image Request, images[at]newenglandwild.org](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Potamogetonaceae/potamogeton-strictifolius-sf-gmorrison.jpg)
![Flowers and fruits: Potamogeton strictifolius. ~ By C. Barre Hellquist. ~ Copyright © 2024 C. Barre Hellquist. ~ C.Barre.Hellquist[at]mcla.edu ~ U. of New Hampshire](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Potamogetonaceae/potamogeton-strictifolius-ff-pbruns.jpg)
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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
Straight-leaved pondweed is an uncommon pondweed most often found in alkaline water of lakes and rivers. Its range includes Connecticut, Massachusetts, Maine, and Vermont, and it is protected in all those states.
Habitat
Lacustrine (in lakes or ponds), riverine (in rivers or streams)
Characteristics
- Habitat
- aquatic
- New England state
-
- Connecticut
- Maine
- Massachusetts
- Vermont
- Leaf position
- the leaves are all submerged underwater
- Leaf arrangement
-
- alternate: there is one leaf per node along the stem
- whorled: there are three or more leaves per node along the stem
- Leaf blade length
- 12–63 mm
- Petal or sepal number
- there are four petals, sepals, or tepals in the flower
- 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
- 0.6–2 mm
- Fruit type (general)
-
- the fruit is dry but does not split open when ripe
- the fruit is fleshy
- Underwater leaf length
- 12–63 mm
-
Clonal plantlets
- Turion length
- 25–48 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
- 6–13 mm
- Inflorescence type
- the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
- Length of peduncle
- 10–45 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 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
- 1.1–1.8 mm
- 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
- 0.5–0.8 mm
- Fruit length
- 1.9–2.1 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
- 1.3–1.8 mm
-
Glands or sap
- Oil glands on nodes
- at least some of the nodes have pairs of 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
- the plant has turions
- Underground organs
- there are only slender roots on the plant
-
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
- whorled: there are three or more leaves per node along the stem
- Leaf blade length
- 12–63 mm
- Leaf blade veins
- the lateral veins are parallel or slightly arched in the direction of the tip
- Leaf blade width
- 0.6–2 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 do not forma 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 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
- 3–7
- Underwater leaf blade width
- 0.6–2 mm
- Underwater leaf length
- 12–63 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)
- Veins in floating leaf
- 0
-
Place
- Habitat
- aquatic
- New England state
-
- Connecticut
- Maine
- Massachusetts
- 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)
New England distribution and conservation status
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- absent
- Rhode Island
- absent
- 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)
- Maine
- extremely rare (S-rank: S1), threatened (code: T)
- Massachusetts
- extremely rare (S-rank: S1), endangered (code: E)
- Vermont
- rare to uncommon (S-rank: S2S3)
Native to North America?
Yes
Sometimes confused with
- Potamogeton friesii:
- leaf blades obtuse to rounded at the apex, sometimes with an apiculus, and winter buds with inner leaves oriented at a right angle to the outer leaves, the outer leaves corrugated at the base (vs. P. strictifolius, with leaf blades obtuse to attenuate at the apex and winter buds flattened, the inner and outer leaves oriented in the same plane, the outer leaves not corrugated at the base).
- Potamogeton ogdenii:
- leaf blades with mostly 3–9 veins, 1.2–2.9 mm wide, with 0–3 rows of lacunae on each side of the midrib, and stipules usually brown, convolute (vs. P. strictifolius, with leaf blades with mostly 3–5 veins, 0.6–2 mm wide, without lacunae, and stipules usually white, the margins connate).
Synonyms
- Potamogeton longiligulatus Fern.
- Potamogeton strictifolius Benn. var. rutiloides Fern.
Family
Genus
From the dichotomous key of Flora Novae Angliae
26. Potamogeton strictifolius Benn. NC
straight-leaved pondweed. Potamogeton strictifolius Benn. var. rutiloides Fern. • CT, MA, ME, VT. Shallow, still or slow-moving, circumneutral to basic water of lakes and rivers.
26×28. Potamogeton strictifolius × Potamogeton zosteriformis → Potamogeton ×haynesii Hellquist & Crow is a rare pondweed hybrid known from VT. It closely resembles P. strictifolius and, like that species, has light-colored, fibrous stipules and usually lacks lacunar bands on leaf blades. The hybrid also has similar winter buds to those of P. strictifolius. The hybrid shows leaf blades with 7–21 veins and rarely produces fruit. Potamogeton strictifolius has leaf blades with 3–5 (–7) veins and routinely produces fruits.