Cyperus polystachyos Rottb.

many-spiked 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

Many-spiked flatsedge is a native plant of sandy pond shores, ditches, and the wetlands between sand dunes near the coasts of Massachusetts, Maine and Rhode Island. It is distributed as far away as Australia, where it is also considered native, if a bit "weedy." It fruits in late summer to early fall, when its spikes become a deep, lustrous brown.

Habitat

Anthropogenic (man-made or disturbed habitats), shores of rivers or lakes, wetland margins (edges of wetlands)

Characteristics

Habitat
wetlands
New England state
  • Maine
  • Massachusetts
  • Rhode Island
Stem shape in cross-section
  • the stem is roughly triangular in cross-section
  • the stem is round or oval in cross-section
Leaf blade width
1–4 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
Fruit type (general)
the fruit is like a seed, and surrounded by scales
Fruit length
0.8–1.2 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
    0.4–0.8 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
    1.5–2.3 mm
    Floral scale nerves
    2-5
    Floral scale shape
    the floral scales are oblong (rectangular but with rounded ends)
    Floral scale translucent
    the floral scales are opaque
    Flower number per cluster
    • 5-20
    • 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
    Inflorescence crowding
    • the inflorescence is at least somewhat spread out, with at least one branch coming from the main stem
    • 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
    2
    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 very obvious pits or depressions on it
    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
    0.8–1.2 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 more than two years
    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
    20–600 mm
    Leaf blade width
    1–4 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
    10–40 mm
  • Place
    Habitat
    wetlands
    New England state
    • Maine
    • Massachusetts
    • Rhode Island
    Specific habitat
    • edges of wetlands
    • man-made or disturbed habitats
    • shores of rivers or lakes
  • Stem, shoot, branch
    Plant height
    3–70 cm
    Stem shape in cross-section
    • the stem is roughly triangular in cross-section
    • the stem is round or oval 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)

New England Distribution and Conservation Status

Distribution

Connecticut
absent
Maine
present
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
extremely rare to rare (S-rank: S1S2)

var. filicinus

Massachusetts
unranked (S-rank: SNR)

Native to North America?

Yes

Sometimes Confused With

Cyperus filcinus:
achenes narrow-obovate in outline and floral scales 2.5–3.5 mm long (vs. C. polystachyos, with achenes oblong in outline and floral scales 1.5–2.3 mm long).

Synonyms

  • Cyperus polystachyos Rottb. var. texensis (Torr.) Fern.
  • Pycreus polystachyos (Rottb.) Beauv.

Family

Cyperaceae

Genus

Cyperus

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Information from Dichotomous Key of Flora Novae Angliae

17.  Cyperus polystachyos Rottb. N

many-spiked flatsedge. Cyperus polystachyos Rottb. var. texensis (Torr.) Fern.; Pycreus polystachyos (Rottb.) Beauv. • MA, ME, RI. Sandy pond shores, interdunal wetlands, ditches.