Najas guadalupensis — Guadalupe waternymph
![Inflorescences: Najas guadalupensis. ~ By Clayton J. Antieau. ~ Copyright © 2024 Clayton J. Antieau. ~ Clayton.Antieau[at]seattle.gov ~ U. of Washington - WTU - Herbarium - biology.burke.washington.edu/herbarium/imagecollection.php](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Hydrocharitaceae/najas-guadalupensis-in-cantieau.jpg)
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Facts
Guadalupe waternymph has a wide distribution that includes North, Central and South America. It is also introduced in other parts of the world, and in some places considered a noxious weed. Note that there are two subspecies in New England.
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.
enlargeCharacteristics
- Habitat
- aquatic
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Leaf position
- the leaves are all submerged underwater
- Leaf arrangement
- opposite: there are two leaves per node along the stem
- Leaf blade length
- 3–33 mm
- Petal or sepal number
- there are no petals, sepals, or tepals in the flower, or they are not clearly present
- Petal color
- NA
- 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
- 0.2–2.1 mm
- Fruit type (general)
- the fruit is dry and splits open when ripe
- Underwater leaf length
- 3–33 mm
-
Clonal plantlets
- Turion length
- 0 mm
-
Flowers
- Anther length
- 1–1.7 mm
- Carpels fused
- NA
- Flower lower lip length
- 0 mm
- Flower number
- 1–3
- Flower position
- the flowers are below 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
- 1.5–4 mm
- Inflorescence type
-
- the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
- the inflorescence has only one flower on it
- the inflorescence is a monochasial cyme (an axis with a terminal flower, below it a branch with a terminal flower, this branch may itself have a branch and so on)
- Length of flower stalk
- At least 0 mm
- Length of peduncle
- At least 0 mm
- Nectar spur
- the flower has no nectar spurs
- Number of carpels
- 1
- Ovary position
- the sepals and/or petals are attached above the ovary
- Palate on corolla
- NA
- Petal and sepal arrangement
- the flower includes neither petals nor sepals
- Petal appearance
- NA
- Petal color
- NA
- Petal fringed edges
- NA
- Petal fusion
- NA
- Petal hairs on inner/upper surface
- NA
- Petal length
- 0 mm
- Petal number
- 0
- Petal or sepal number
- there are no petals, sepals, or tepals in the flower, or they are not clearly present
- Pistil number
- 1
- Sepal appearance
- NA
- Sepal length
- 0 mm
- Sepal number
- 0
- Sepals fused only to sepals
- NA
- Spur length
- 0 mm
- Stamen number
- 1 or 2
- Stamen position relative to petals
- NA
- Stamens fused
-
- NA
- the stamens are not fused to one another
- Stamens fused to petals
- the stamens are not fused to the petals or tepals
- Style length
- 0.3–1.5 mm
- Style number
- 1
-
Fruits or seeds
- Fruit length
- 1.5–2.5 mm
- Fruit type (general)
- the fruit is dry and splits open when ripe
- Fruit type (specific)
- the fruit is an achene (dry, usually 1-seeded, does not separate or split open at maturity)
-
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 only a single year or less
- 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
- 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
- opposite: there are two leaves per node along the stem
- Leaf blade length
- 3–33 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
- 0.2–2.1 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 attached to the leaf blade for some part of their length
- Stipules
- the plant has stipules
- Trap-bladder length
- 0 mm
- 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 linear (very narrow with more or less parallel sides)
- Underwater leaf blade veins
- 1
- Underwater leaf blade width
- 0.2–2.1 mm
- Underwater leaf length
- 3–33 mm
- Underwater leaf stalk
- no
- Underwater leaf stalk length
- 0 mm
- Underwater leaf tip shape
-
- the tip of the underwater leaf is rounded, with no point
- the tip of the underwater leaf is truncate (ends abruptly in a more or less straight line as though cut off)
- 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
- in rivers or streams
-
Stem, shoot, branch
- Flowering stem growth form
- the flowering stem trails along the substrate, or floats in the water
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
- fairly widespread (S-rank: S4)
- Maine
- extremely rare (S-rank: S1), special concern (code: SC)
- Vermont
- rare (S-rank: S2)
ssp. guadalupensis
- Massachusetts
- not applicable (S-rank: SNA)
- New Hampshire
- unrankable (S-rank: SU), Ind (code: Ind)
ssp. olivacea
- Massachusetts
- not applicable (S-rank: SNA)
Subspecies and varieties
Subspecies guadalupensis is known from CT, MA, ME, NH, RI, VT. Subspecies olivacea is known from CT, MA.
From Flora Novae Angliae dichotomous key
3. Najas guadalupensis (Spreng.) Magnus N
Guadalupe waternymph. 3a. Caulinia guadalupensis Spreng.; 3b. Najas guadalupensis (Spreng.) Magnus var. olivacea (Rosendahl & Butters) Haynes; N. olivacea Rosendahl & Butters • CT, MA, ME, NH, RI, VT. Circumneutral, fresh to brackish water of lakes and rivers.
1a. Leaf blade with 50–100 unicellular spicules on each margin; stems up to 0.8 mm in diameter … 3a. N. guadalupensis ssp. guadalupensis
1b. Leaf blade with 20–40 unicellular spicules on each margin; stems 1 mm or more in diameter … 3b. N. guadalupensis ssp. olivacea (Rosendahl & Butters) Haynes & Hellquist
Subspecies guadalupensis is known from CT, MA, ME, NH, RI, VT. Subspecies olivacea is known from CT, MA.
Native to North America?
Yes
Sometimes confused with
- Najas gracillima:
- each margin of the leaf blade with 13–17 spinules and apex of leaf sheath truncate or auriculate (vs. N. guadalupensis, with each margin of the leaf blade with 20–100 minute, unicellular spinules and apex of leaf sheath convexly tapering into base of blade).
- Najus flexilis:
- testa of seeds glossy, very minutely pitted and appearing +/- smooth at low magnification, seeds narrow-obovoid to broad-obovoid, widest above the middle, and leaves 0.2–0.6 mm wide (vs. N. guadalupensis, with the testa of seeds dull, minutely pitted and appearing so even at low magnification, seeds fusiform, widest at the middle, and leaves 0.2–2.1 mm wide).
Synonyms
- Caulinia guadalupensis Spreng.