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Cyperus erythrorhizos — red-root flatsedge

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Facts

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)

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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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
Show all characteristics

  • 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)

In New England

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?)

From Flora Novae Angliae dichotomous key

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.

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

Cyperaceae

Genus

Cyperus