Cyperus diandrus — umbrella flatsedge
![Plant form: Cyperus diandrus. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Cyperaceae/cyperus-diandrus-ha-ahaines-b.jpg)
![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:443/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:443/taxon-images-1000s1000/Cyperaceae/cyperus-diandrus-in-ahaines-a.jpg)
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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.
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enlargeFacts
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)
Characteristics
- 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)
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
- widespread (S-rank: S5)
- Vermont
- extremely rare (S-rank: S1), endangered (code: E)
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
Family
Genus
From the dichotomous key of Flora Novae Angliae
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.