Cyperus schweinitzii Torr.

Schweinitz's 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

Schweinitz's flatsedge has been collected once in Massachusetts from a freight yard. While introduced to New England, it is native to much of the United States where it is found on sandy shorelines, along dunes, and in open woodlands. It is named for a famous botanist, Lewis David de Schweinitz (1780-1834), who made several important plant collections during his lifetime (even though he was an authority on fungi). The Kiowa native american people used this flatsedge to fatten horses. It has tightly-held, upright inflorescences.

Habitat

Dunes, shores of rivers or lakes, woodlands

Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
Massachusetts
Stem shape in cross-section
the stem is roughly triangular in cross-section
Leaf blade width
2–6 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
2–3.5 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
    0.8–1.4 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
    2.3–3.2 mm
    Floral scale nerves
    7 or more
    Floral scale shape
    • the floral scales are oblong (rectangular but with rounded ends)
    • the floral scales are ovate (roughly egg-shaped)
    Floral scale translucent
    the floral scales are translucent
    Flower number per cluster
    5-20
    Inflorescence bract angle
    the bracts are vertical or angled only slightly outwards
    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 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
    2–3.5 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
    20–350 mm
    Leaf blade width
    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
    • there are no leaves on the main stem, or there is a small tooth or tiny blade, or a leaf sheath with no blade
    Width of seed-producing inflorescence
    7–16 mm
  • Place
    Habitat
    • terrestrial
    • wetlands
    New England state
    Massachusetts
    Specific habitat
    • dunes
    • shores of rivers or lakes
    • woodlands
  • Stem, shoot, branch
    Plant height
    10–50 cm
    Stem shape in cross-section
    the stem is roughly triangular in cross-section
    Stem texture near tip
    the edges of the stem feel rough near the tip

Wetland Status

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

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
unranked (S-rank: SNR)

Native to North America?

Yes and no (some introduced)

Synonyms

  • Mariscus schweinitzii (Torr.) T. Koyama

Family

Cyperaceae

Genus

Cyperus

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Information from Dichotomous Key of Flora Novae Angliae

20.  Cyperus schweinitzii Torr. N

Schweinitz’s flatsedge. Mariscus schweinitzii (Torr.) T. Koyama • MA. Sandy shorelines, sand dunes, open woodlands.

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).