Cyperus flavescens — yellow flatsedge
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Facts
Yellow flatsedge is a species of disturbed, moist to wet sites in Massachusetts. It reaches the northeastern edge of its range on Cape Cod and the Islands, where populations may have been introduced. It may get its common name from the pale color of its immature spikelets, which have a yellowish cast.
Habitat
Anthropogenic (man-made or disturbed habitats)
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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enlargeCharacteristics
- Habitat
-
- terrestrial
- wetlands
- New England state
- Massachusetts
- Stem shape in cross-section
- the stem is roughly triangular in cross-section
- Leaf blade width
- 0.5–2.6 mm
- Leaf blade cross-section
-
- NA
- 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
- Fruit type (general)
- the fruit is like a seed, and surrounded by scales
- Fruit length
- 1–1.2 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 lenticular (lens-shaped) in cross-section
-
Flowers
- Anther length
- 0.4–0.5 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
- 1.5–2.2 mm
- Floral scale nerves
- 0
- Floral scale shape
- the floral scales are ovate (roughly egg-shaped)
- Floral scale translucent
- the floral scales are opaque
- Flower number per cluster
- 5-20
- Inflorescence bract angle
- the bracts are angled outwards near horizontal or reflexed downwards
- 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
- 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
- Perianth composition
- there is no perianth on the plant
- Stamen number
- 3
- Stigma number
- 2
- 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 surface texture
- the achene has stripes or ridges that run from end to end
- Achene tubercle relative width
- NA
- Achene tubercle width
- 0 mm
- Capsule relative length
- NA
- Fruit cross-section
- the fruit is lenticular (lens-shaped) in cross-section
- Fruit length
- 1–1.2 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 only a single year or less
- 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
-
- NA
- the leaf blade is flat or rolled in at the edges
- Leaf blade length
- 30–180 mm
- Leaf blade width
- 0.5–2.6 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
- 8–26 mm
-
Place
- Habitat
-
- terrestrial
- wetlands
- New England state
- Massachusetts
- Specific habitat
- man-made or disturbed habitats
-
Stem, shoot, branch
- Plant height
- 2–30 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
Occurs only in wetlands. (Wetland indicator code: OBL)
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
9. Cyperus flavescens L. E
yellow flatsedge. Cyperus flavescens L. var. poiformis (Pursh) Fern.; Pycreus flavescens (L.) Reichenb. • MA. Wet-mesic, often human-disturbed, soils.
Native to North America?
Yes
Sometimes confused with
- Cyperus bipartitus:
- achenes narrow-obovate to oblong in outline, unmarked, and floral scales narrow-oblong to ovate (vs. C. flavescens, with achenes broad-obovate to nearly suborbicular in outline, minutely marked with elongate, superficial cells and irregular, pale transverse lines at maturity, and floral scales broad-ovate).
- Cyperus diandrus:
- achenes narrow-obovate to oblong in outline, unmarked, and floral scales narrow-oblong to ovate (vs. C. flavescens, with achenes broad-obovate to nearly suborbicular in outline, minutely marked with elongate, superficial cells and irregular, pale transverse lines at maturity, and floral scales broad-ovate).
Synonyms
- Cyperus flavescens L. var. poiformis (Pursh) Fern.
- Pycreus flavescens (L.) Reichenb.