Eriophorum viridicarinatum (Engelm.) Fern.

green-keeled cottongrass, green-keeled cottonsedge

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

Green-keeled cottonsedge inhabits fens and meadows throughout New England, wherever the pH is high. It gets its common name from the fact that the floral scales have a prominent green midrib. This species is endemic to North America, ranging from Alaska to Newfoundland; it comes close to its southern range limit in New England, which is why it is listed as rare in Rhode Island.

Habitat

Fens (calcium-rich wetlands), meadows and fields

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
2–6 mm
Leaf blade cross-section
  • the leaf blade is flat or rolled in at the edges
  • the leaf blade is triangular in cross-section
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 hairs
  • the fruit is like a seed, and surrounded by scales
Fruit length
2.5–3.5 mm
Leaf position on plant
some leaf attachment points are above the midpoint of the stem
Perianth composition
there are bristles attached at the base of the achene
Fruit cross-section
the fruit is triangular to terete (circular) in cross-section
Show All Characteristics
  • Flowers
    Anther length
    0.8–2 mm
    Floral bristle color
    the bristles are white
    Floral bristle number
    8 or more
    Floral bristle relative length
    the bristles are longer than the achene
    Floral bristles
    the bristles are straight or slightly curved
    Floral scale hairs
    there are no hairs on the floral scales
    Floral scale length
    4–6 mm
    Floral scale nerves
    1
    Floral scale shape
    • the floral scales are lanceolate (widest below the middle, and tapering at both ends)
    • the floral scales are ovate (roughly egg-shaped)
    Floral scale translucent
    the floral scales are opaque
    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 roughly circular (not flattened) in cross-section
    Inflorescence type
    there are two or more flowers, spikes or flower clusters on a branched inflorescence
    Perianth composition
    there are bristles attached at the base of the achene
    Stamen number
    3
    Stigma number
    3
    Style division
    the top two thirds of the style is divided
    floral bristle barbs
    the bristles do not have barbs on them
  • 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
    2.5–3.5 mm
    Fruit type (general)
    • the fruit is like a seed, and surrounded by hairs
    • 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
    • the leaf blade is triangular in cross-section
    Leaf blade length
    Up to 300 mm
    Leaf blade width
    2–6 mm
    Leaf form
    all the leaves hold their form out of water
    Leaf position on plant
    some leaf attachment points are above the midpoint of the stem
    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
    the plant has ligules at the leaf blade bases
    Stem leaf blades
    there are fully-developed leaves with leaf blades on the main stem
  • Place
    Habitat
    wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • fens (calcium-rich wetlands)
    • meadows or fields
  • Stem, shoot, branch
    Plant height
    20–90 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
    Stem thickness at midpoint
    0.9–1.2 mm

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
unranked (S-rank: SNR)
Rhode Island
extremely rare (S-rank: S1), concern (code: C)

Native to North America?

Yes

Sometimes Confused With

Eleocharis angustifolium

Synonyms

  • Eriophorum latifolium Hoppe var. viridicarinatum Engelm.

Family

Cyperaceae

Genus

Eriophorum

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