Cyperus pseudovegetus — marsh flatsedge
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Facts
Marsh flatsedge is a non-native species that has been collected in Massachusetts on wet soils, often of stream and pond shores. It's recognizable for its hemispherical heads (inflorescences).
Habitat
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.
enlargeCharacteristics
- Habitat
- wetlands
- New England state
- Massachusetts
- Stem shape in cross-section
- the stem is roughly triangular in cross-section
- Leaf blade width
- 4.5–8 mm
- Leaf blade cross-section
- the leaf blade is flat or rolled in at the edges
- Inflorescence position
- the inflorescence is at the tip of the plant
- Inflorescence branching
-
- the inflorescence is branched
- the inflorescence is on one or more stems with no branches
- Fruit type (general)
- the fruit is like a seed, and surrounded by scales
- Fruit length
- 1.2–1.4 mm
- Leaf position on plant
- the attachment points of all the leaves are at or near the base of the plant
- Perianth composition
- there is no perianth on the plant
- Fruit cross-section
- the fruit is triangular to terete (circular) in cross-section
-
Flowers
- Anther length
- 0.7–1 mm
- Floral bristle color
- NA
- Floral bristle number
- 0
- Floral bristle relative length
- NA
- Floral bristles
- NA
- Floral scale hairs
- there are no hairs on the floral scales
- Floral scale length
- 2–2.5 mm
- Floral scale nerves
- 2-5
- Floral scale shape
-
- the floral scales are another shape than those given
- the floral scales are oblong (rectangular but with rounded ends)
- Floral scale translucent
- the floral scales are opaque
- Flower number per cluster
- more than 20
- Inflorescence bract number
- there are two to five bracts per inflorescence
- Inflorescence bract position (Sparganium)
- NA
- Inflorescence bracts
- there are at least two bracts, and they are either flat or folded or rolled in at the edges
- Inflorescence branching
-
- the inflorescence is branched
- the inflorescence is on one or more stems with no branches
- Inflorescence crowding
- the inflorescence is crowded together in one tight cluster
- Inflorescence position
- the inflorescence is at the tip of the plant
- Inflorescence shape
- the aggregations within the inflorescence are at least somewhat flattened in cross-section
- Inflorescence type
-
- there are two or more flowers, spikes or flower clusters on a branched inflorescence
- there is one spike or raceme at the tip of the stem
- Perianth composition
- there is no perianth on the plant
- Stamen number
- 1
- Stigma number
- 3
- Style division
- the top two thirds of the style is divided
- floral bristle barbs
- NA
- plantlets budding at flower bases
- no
-
Fruits or seeds
- Achene tubercle relative width
- NA
- Achene tubercle width
- 0 mm
- Capsule relative length
- NA
- Fruit cross-section
- the fruit is triangular to terete (circular) in cross-section
- Fruit length
- 1.2–1.4 mm
- Fruit type (general)
- the fruit is like a seed, and surrounded by scales
- Fruit type (specific)
- the fruit is an achene (dry, seed-like fruit) without a tubercle (a swelling or projection, usually of a different color or texture)
- Locules in capsule
- NA
- Seed length
- 0 mm
- Seed tail relative length
- 0 mm
- Seed tails
- NA
- Tubercle height
- 0 mm
-
Growth form
- Lifespan
- the plant lives more than two years
- Rhizome thickness
- 5–8 mm
- Underground organs
- the plant has a rhizome (a horizontal underground stem with roots growing from it)
-
Leaves
- Auricle length
- 0 mm
- Auricle texture
- NA
- Auricles
- there are no auricles on the leaf sheath
- Leaf blade cross-section
- the leaf blade is flat or rolled in at the edges
- Leaf blade length
- 200–600 mm
- Leaf blade width
- 4.5–8 mm
- Leaf form
- all the leaves hold their form out of water
- Leaf position on plant
- the attachment points of all the leaves are at or near the base of the plant
- Leaf septa
- the leaf blades do not have transverse septa
- Leaf sheath hairs
- the leaf sheathes are without hairs
- Pedicel length (Typha)
- 0 mm
- Stem leaf blade ligules
- there are no ligules at the leaf blade bases
- Stem leaf blades
- there are fully-developed leaves with leaf blades on the main stem
- Width of seed-producing inflorescence
- 7–35 mm
-
Place
- Habitat
- wetlands
- New England state
- Massachusetts
- Specific habitat
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 30–80 cm
- Stem shape in cross-section
- the stem is roughly triangular in cross-section
- Stem texture near tip
- the stem feels smooth near the tip
Wetland status
Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)
In New England
Distribution
- Connecticut
- absent
- Maine
- absent
- Massachusetts
- present
- New Hampshire
- absent
- Rhode Island
- absent
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- not applicable (S-rank: SNA)
From Flora Novae Angliae dichotomous key
18. Cyperus pseudovegetus Steud. E
marsh flatsedge. Cyperus virens Michx. var. arenicola (Boeckl.) Shinners • MA. Hydric soils, usually sandy or muddy, and often associated with stream and pond shores.
Native to North America?
Yes
Synonyms
- Cyperus virens Michx. var. arenicola (Boeckl.) Shinners