Cyperus erythrorhizos — red-root flatsedge
![Plant form: Cyperus erythrorhizos. ~ By Bruce Patterson. ~ Copyright © 2024 Bruce Patterson. ~ foxpatterson[at]comcast.net](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Cyperaceae/cyperus-erythrorhizos-ha-bpatterson.jpg)
![Inflorescences: Cyperus erythrorhizos. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Cyperaceae/cyperus-erythrorhizos-in-ahaines.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
Red-root flatsedge is mostly found in moist to wet shores on sandy soil, but also in peaty or mucky situations. It is found in all New England states except Vermont, and it is regarded as threatened, or perhaps even extirpated, in Maine. This annual species gets its name from its tangled mat of roots, which are colored with anthocyanin, a reddish pigment. Kamia native americans have used the mashed seeds to make porridge.
Habitat
Shores of rivers or lakes, wetland margins (edges of wetlands)
Characteristics
- Habitat
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Stem shape in cross-section
-
- the stem is roughly triangular in cross-section
- the stem is round or oval in cross-section
- Leaf blade width
- 2–11 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
- 0.4–1 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
- 0.2–0.3 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
- 0.5–1.7 mm
- Floral scale nerves
- 0
- Floral scale shape
- the floral scales are ovate (roughly egg-shaped)
- Floral scale translucent
- the floral scales are opaque
- Flower number per cluster
-
- 5-20
- more than 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
-
- 2
- 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 beak length
- 0 mm
- Achene surface texture
- the achene is smooth (it has no detectable texture)
- 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
- 0.4–1 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
- 50–900 mm
- Leaf blade width
- 2–11 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
- 4–45 mm
-
Place
- Habitat
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Specific habitat
-
- edges of wetlands
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 0.5–105 cm
- Stem shape in cross-section
-
- the stem is roughly triangular in cross-section
- the stem is round or oval 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
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Maine
- extremely rare (S-rank: S1), endangered (code: E)
- Massachusetts
- widespread (S-rank: S5)
- New Hampshire
- extremely rare (S-rank: S1), endangered (code: E)
- Vermont
- rare (uncertain) (S-rank: S2?)
Native to North America?
Yes
Sometimes confused with
- Cyperus fuscus:
- spikelets radiating from the summit of short axes, forming subcapitate clusters, rachilla lacking a prominent wing-margin, and roots brown (vs. C. erythrorhizos, with spikelets serially disposed along elongate axes, forming cylindric clusters, rachilla wing-margined, and roots anthocyanic).
Synonyms
- Cyperus halei Torr. ex Britt.
Family
Genus
From the dichotomous key of Flora Novae Angliae
6. Cyperus erythrorhizos Muhl. N
red-root flatsedge. Cyperus halei Torr. ex Britt. • CT, MA, ME, NH, RI. Mesic to hydric shorelines and wet areas, often on sandy substrate, but occasionally mucky or peaty.