Cyperus schweinitzii — Schweinitz's flatsedge
![Flowers and fruits: Cyperus schweinitzii. ~ By Steve Garske. ~ Copyright © 2024 Steve Garske. ~ asimina[at]alphacomm.net](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/cyperus-schweinitzii-ff-sgarske-b.jpg)
![Leaves and auricles: Cyperus schweinitzii. ~ By Julian A. Steyermark. ~ Copyright © 2024. ~ Allison Brock, Allison.Brock[at]mobot.org ~ Steyermark, Julian A. 1963. The Flora of Missouri. The Iowa State U. Press, Ames, IA. 1725pp.](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/cyperus-schweinitzii-la-jsteyermark1.jpg)
![Inflorescences: Cyperus schweinitzii. ~ By Elizabeth Farnsworth. ~ Copyright © 2024 New England Wild Flower Society. ~ Image Request, images[at]newenglandwild.org](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/cyperus-schweinitzii-in-efarnsworth.jpg)
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Facts
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
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.
Found this plant? Take a photo and post a sighting.
enlargeCharacteristics
- 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
-
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)
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
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).
Native to North America?
Yes and no (some introduced)
Synonyms
- Mariscus schweinitzii (Torr.) T. Koyama