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- Egeria densa
Egeria densa — Brazilian-waterweed
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Facts
Brazilian-waterweed, probably one of the most widely-cultivated aquarium plants, has for this reason become a widespread invasive species of lakes and rivers. Its presence can have pronounced effects on the community composition of aquatic plants where it occurs.
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
- Massachusetts
- New Hampshire
- Vermont
- Leaf position
- the leaves are all submerged underwater
- Leaf arrangement
- whorled: there are three or more leaves per node along the stem
- Leaf blade length
- 10–40 mm
- Petal or sepal number
- there are three petals, sepals, or tepals in the flower
- Petal color
- white
- 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
- 1.5–4.5 mm
- Fruit type (general)
- the fruit is fleshy
- Underwater leaf length
- 10–40 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 carpels are fused to one another
- Flower lower lip length
- 0 mm
- Flower number
- 1–4
- 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 type
-
- 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
- 30–80 mm
- Length of peduncle
- 0 mm
- Nectar spur
- the flower has no nectar spurs
- Number of carpels
- 0–1
- Ovary position
-
- NA
- the sepals and/or petals are attached above the ovary
- Palate on corolla
- no
- Petal and sepal arrangement
- the flower includes two cycles of petal- or sepal-like structures
- Petal appearance
- the petals are thin and delicate, and pigmented (colored other than green or brown)
- Petal color
- white
- 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
- 9–11 mm
- Petal number
- 3
- Petal or sepal number
- there are three petals, sepals, or tepals in the flower
- Pistil number
-
- 0
- 1
- Sepal appearance
- the sepals resemble leaves in color and texture
- Sepal length
- 3–4 mm
- Sepal number
- 3
- Sepals fused only to sepals
- the sepals are separate from one another
- Spur length
- 0 mm
- Stamen number
- 9
- Stamen position relative to petals
- NA
- Stamens fused
- the stamens are not fused to one another
- Stamens fused to petals
- the stamens are not fused to the petals or tepals
- Style number
- 0–3
-
Fruits or seeds
- Fruit type (general)
- the fruit is fleshy
- Fruit type (specific)
- the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)
-
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
- there are only slender roots on the plant
-
Leaves
- Bract position (Sparganium)
- NA
- Bract relative length
- At least 1379 mm
- Bracts
- the flowers or their pedicels have bracts at their bases
- 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
- the bracts are roughly as lobed as the foliage leaves
- Floral bract length
- 7.5–12 mm
- Leaf arrangement
- whorled: there are three or more leaves per node along the stem
- Leaf blade length
- 10–40 mm
- Leaf blade veins
- the lateral veins are parallel or slightly arched in the direction of the tip
- Leaf blade width
- 1.5–4.5 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
- 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 blade edges are toothed
- Underwater leaf blade shape
- the underwater leaf blade is linear (very narrow with more or less parallel sides)
- Underwater leaf blade width
- 1.5–4.5 mm
- Underwater leaf length
- 10–40 mm
- Underwater leaf stalk
- no
- Underwater leaf stalk length
- 0 mm
- Underwater leaf tip shape
- the tip of the underwater leaf is obtuse (bluntly pointed)
- Veins in floating leaf
- 0
-
Place
- Habitat
- aquatic
- New England state
-
- Connecticut
- Massachusetts
- New Hampshire
- 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, invasive, prohibited
- Maine
- absent
- Massachusetts
- present, invasive, prohibited
- New Hampshire
- present, invasive, prohibited
- Rhode Island
- absent
- Vermont
- present, invasive, prohibited
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
1. Egeria densa Planch. E
Brazilian-waterweed. Anacharis densa (Planch.) Victorin • CT, MA, NH, VT. Shallow, still or slow-moving water of lakes and rivers. This species has been introduced into the United States through the aquarium trade. Only staminate plants are known outside its native range. Vegetative reproduction is likely through plant fragmentation given that no specialized structures for this form of reproduction (e.g., turions, bulbils) have been observed.
Native to North America?
No
Sometimes confused with
Synonyms
- Anacharis densa (Planch.) Victorin