Cyperus diandrus — umbrella flatsedge
![Flowers and fruits: Cyperus diandrus. ~ 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-diandrus-ff-efarnsworth.jpg)
![Inflorescences: Cyperus diandrus. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/cyperus-diandrus-in-ahaines-a.jpg)
![Plant form: Cyperus diandrus. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/cyperus-diandrus-ha-ahaines-b.jpg)
Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.
Facts
Umbrella flatsedge is found on moist to wet, sandy or peaty shorelines throughout New England. Its spikes are distinctive for the fact that the scales are outlined in a rust-colored pigment, but the interior part of the scale is not colored. This gives the spikes a herringbone quality.
Habitat
Shores of rivers or lakes, wetland margins (edges of wetlands)
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
- wetlands
- 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
- 1.5–3 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
- 1–1.2 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
-
Flowers
- Anther length
- 0.3–0.4 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
- 2.5–3 mm
- Floral scale nerves
- 2-5
- 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 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 at least somewhat spread out, with at least one branch coming from the main stem
- 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
-
- 2
- 3
- Stigma number
- 2
- Style division
- the style is divided nearly from the base
- floral bristle barbs
- NA
- plantlets budding at flower bases
- no
-
Fruits or seeds
- Achene beak length
- 0 mm
- Achene surface texture
- the achene has very tiny 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
- 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
- there are only slender roots on the plant
-
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
- 50–200 mm
- Leaf blade width
- 1.5–3 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
- 12–22 mm
-
Place
- Habitat
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- edges of wetlands
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 4–35 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)
In New England
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
- widespread (S-rank: S5)
- Vermont
- extremely rare (S-rank: S1), endangered (code: E)
From Flora Novae Angliae dichotomous key
4. Cyperus diandrus Torr. N
umbrella flatsedge. Pycreus diander (Torr.) C.B. Clarke • CT, MA, ME, NH, RI, VT. Moist to wet, usually sandy or peaty, shorelines.
Native to North America?
Yes
Sometimes confused with
- Cyperus bipartitus:
- floral scales with anthocyanic pigments most prominent in basal and medial portion, fading toward apex, the pigmented region not outlining a conspicuous pale region on each side of the scale, and style connate in the basal 1/3 (vs. C. diandrus, with floral scales with anthocyanic pigments most prominent along medial and apical margin and along upper edges of midribs, with a conspicuous pale area between the midrib and margin, and style divided nearly to its base).
- Cyperus flavescens:
- 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 (vs. C. diandrus, with achenes narrow-obovate to oblong in outline, unmarked, and floral scales narrow-oblong to ovate).
Synonyms
- Pycreus diander (Torr.) C.B. Clarke