Cyperus lupulinus (Spreng.) Marcks

Great Plains 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

Great Plains flatsedge prefers open fields, roadsides and disturbed areas on sandy, well-drained soil. There are two subspecies in New England.

Habitat

Anthropogenic (man-made or disturbed habitats), grassland, meadows and fields

Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Stem shape in cross-section
the stem is roughly triangular in cross-section
Leaf blade width
1–3.5 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
1.7–2.2 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 triangular to terete (circular) in cross-section
Show All Characteristics
  • Flowers
    Anther length
    0.3–1 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
    1.8–4 mm
    Floral scale nerves
    7 or more
    Floral scale shape
    • the floral scales are elliptic (widest in the middle and tapering toward each end)
    • the floral scales are ovate (roughly egg-shaped)
    Floral scale translucent
    the floral scales are translucent
    Flower number per cluster
    • 2-5
    • 5-20
    • more than 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
    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 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 triangular to terete (circular) in cross-section
    Fruit length
    1.7–2.2 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)
    • the plant has one or more swollen storage organs underground, such as bulbs or tubers
  • 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
    50–400 mm
    Leaf blade width
    1–3.5 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
    12–35 mm
  • Place
    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • grasslands
    • man-made or disturbed habitats
    • meadows or fields
  • Stem, shoot, branch
    Plant height
    3–50 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
    Stem thickness at midpoint
    0.4–1.2 mm

Wetland Status

Usually occurs in non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)

New England Distribution and Conservation Status

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
present

Conservation Status

Exact status definitions can vary from state to state. For details, please check with your state.

Massachusetts
unranked (S-rank: SNR)

ssp. lupulinus

Massachusetts
unranked (S-rank: SNR)
Vermont
historical (S-rank: SH)

ssp. macilentus

Massachusetts
unranked (S-rank: SNR)

Native to North America?

Yes

Sometimes Confused With

Cyperus grayi:
involucral bracts ascending to sometimes spreading-ascending, smooth or weakly scabrous-margined, and anthers 0.7-1 mm long (vs. C. lupulinus, with involucral bracts mostly spreading to reflexed, scabrous-margined, numbering 2-4 per cluster, and anthers 0.3-0.6 mm long).
Cyperus houghtonii:
floral scales suborbicular, involucral bracts weakly ascending, and achenes with 1 or more evidently concave faces mostly 1.3-1.5 times as long as wide (vs. C. lupulinus, with floral scales ovate-elliptic, involucral bracts spreading to reflexed, and achenes with flat or slightly concave faces, mostly 1.8-2.1 times as long as wide).

Synonyms

  • Cyperus filiculmis Vahl var. macilentus Fern.

Family

Cyperaceae

Genus

Cyperus

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Information from Dichotomous Key of Flora Novae Angliae

14.  Cyperus lupulinus (Spreng.) Marcks N

Great Plains flatsedge. 14a. Cyperus filiculmis Vahl; 14b. Cyperus filiculmis Vahl var.  macilentus Fern.; C. lupulinus (Spreng.) Marcks ssp. macilentus (Fern.) Marcks • CT, MA, 
ME, NH, RI, VT. Open, well-drained, usually sandy soils of fields, roadsides, grasslands, 
and waste places.

1a.  Spikelets 8–16 mm long, with 5–22 floral scales that are green-yellow to stramineous 
and 2.5–4 mm long; anthers 0.6–1 mm long; spikelets 3–4 mm thick 
 … 14a. C. lupulinus var. lupulinus

1b.  Spiklets 3–7 mm long, with 3–7 floral scales that are pale green to light red-brown and 1.8–2.5 mm long; anthers 0.3–0.6 mm long; spikelets 2.5–3.5 mm thick 
 … 14b. C. lupulinus var. macilentus (Fern.) A. Haines

Variety lupulinus is known from CT, MA, RI, VT. Variety macilentus is known from CT, MA, ME, 
 NH, RI, VT.

14×20. Cyperus lupulinus × Cyperus schweinitzii Cyperus ×‌mesochorus Geise is a very rare flatsedge hybrid known from MA. It typically has fewer inflorescence branches than Cyperus schweinitzii (that species usually with 3–5 elongate branches), widely ascending inflorescence bracts (rather 
than horizontally spreading to reflexed in C. lupulinus and erect to narrowly ascending 
in C. schweinitzii), and floral scales with an awn tip 0.4–0.5 mm long (rather than 0.05–0.2 mm in C. lupulinus and 0.1–1 mm in C. schweinitzii).