Cyperus flavescens L.

yellow flatsedge

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

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)

Characteristics

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
Show All Characteristics
  • 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)

New England Distribution and Conservation Status

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)

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.

Family

Cyperaceae

Genus

Cyperus

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Information from Dichotomous Key of Flora Novae Angliae

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.