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Carex arcta — northern cluster sedge

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Facts

Northern cluster sedge is found only in the northern New England states, and it is listed as endangered in Vermont. It is typically found in wet-mesic, mixed or evergreen forests. The tightly-aggregated inflorescence of 5-15 spikes is characteristic.

Habitat

Forests, shores of rivers or lakes

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
  • Maine
  • New Hampshire
  • Vermont
stem leaf blade width
2–4 mm
Lowest bract sheath
the lowest bract has no sheath (or a very short sheath up to four millimeters in length)
Spike on stalk
the lowest spike on the plant is not borne on a peduncle
Top spike
the uppermost spike contains both staminate and carpellate flowers, with the staminate flowers located below the carpellate flowers
Perigynium hairs
the perigynium has no hairs
Perigynium length
2–3.5 mm
Leaf sheath color
  • the leaf sheath has no pink, red or purple tinting
  • the leaf sheath is tinted pink, red or purple
Leaf blade texture
the leaf blade is smooth and hairless, or rough and sandpapery
Perigynium beak teeth
the perigynium beak is divided at the top into two teeth
Show all characteristics

  • Flowers

    Bumps on fruit
    the perigynium surface has papillae on it
    Inflorescence length
    15–40 mm
    Length of scale
    the scale is shorter than the perigynium
    Lowest spike length
    5–10 mm
    Lowest spike stalk length
    0 mm
    Lowest spike width
    4–6 mm
    Perigynium beak
    the perigynium has a beak
    Perigynium beak length
    0.75–1.25 mm
    Perigynium beak orientation
    the beak of the perigynium is straight, and in line with the perigynium
    Perigynium beak serrations
    the perigynium beak has tiny serrations along the edges
    Perigynium beak teeth
    the perigynium beak is divided at the top into two teeth
    Perigynium color
    brown
    Perigynium cross-section
    the perigynium is planoconvex (flat on one surface and rounded on the other) in cross-section
    Perigynium hairs
    the perigynium has no hairs
    Perigynium length
    2–3.5 mm
    Perigynium nerve texture
    the nerves on the perigynium are raised, even after drying the perigynium
    Perigynium nerves upper side
    At least 0
    Perigynium orientation
    • the perigynia are angled outwards
    • the perigynia are oriented vertically or pressed against the axis or adjacent perigynia
    Perigynium puffy
    the achene is tightly enclosed by the perigynium
    Perigynium shape
    the perigynium body is ovate (egg-shaped)
    Perigynium width
    1.25–1.5 mm
    Perigynium winged
    the perigynium has no wings
    Pollen- and seed-producing spikes
    some of the spikes produce perigynia
    Pollen-producing spike length
    0 mm
    Pollen-producing spike number
    0
    Pollen-producing spike peduncle length
    0 mm
    Pollen-producing spike width
    0 mm
    Scale awn
    The carpellate scale does not have an awn (it may have a short point)
    Scale awn texture
    NA
    Scale color
    • brown
    • green
    • white or translucent
    Scale tip
    • the carpellate scale tip is acute (has a sharp point)
    • the carpellate scale tip is obtuse (has a blunt point)
    Spike on stalk
    the lowest spike on the plant is not borne on a peduncle
    Spike orientation
    the spikes are oriented vertically or pressed against the axis
    Spikes per stem
    2-15
    Staminate scale tip
    • the staminate scale tip is acute (has a sharp point)
    • the staminate scale tip is obtuse (has a blunt point)
    Stigma branching
    the stigmas have two branches
    Top spike
    the uppermost spike contains both staminate and carpellate flowers, with the staminate flowers located below the carpellate flowers

  • Fruits or seeds

    Achene dimples
    the achene has no folds or dimples
    Achene length
    1.25–1.51 mm
    Style persistence
    the style falls off the mature achenes

  • Growth form

    Rhizomes
    there are no rhizomes, or the rhizomes are very short

  • Leaves

    Leaf arrangement
    the leaves are all produced from the base of the plant
    Leaf blade cross-section
    the leaf blade is flat or M-shaped, with two prominent side-veins
    Leaf blade length to width ratio
    75–125
    Leaf blade texture
    the leaf blade is smooth and hairless, or rough and sandpapery
    Leaf bumps
    the upper surface of the leaf blade does not have papillae
    Leaf sheath bumps
    there are no papillae at the top edge of the leaf sheath
    Leaf sheath color
    • the leaf sheath has no pink, red or purple tinting
    • the leaf sheath is tinted pink, red or purple
    Leaf sheath dots
    there are red dots on the translucent tissues of the leaf sheathes
    Leaf sheath folds
    there are no corrugations on the leaf sheath
    Leaf sheath texture
    the leaf sheath feels smooth, and has no hairs
    Lowest bract sheath
    the lowest bract has no sheath (or a very short sheath up to four millimeters in length)
    Lowest leaf blade width
    2–4 mm
    Lowest leaf sheath texture
    the leaf sheath feels smooth (it may have soft hairs)
    stem leaf blade width
    2–4 mm

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Maine
    • New Hampshire
    • Vermont
    Specific habitat
    • forests
    • shores of rivers or lakes

  • Stem, shoot, branch

    Plant height
    15–80 cm
    Relative stem height
    • the main stem is equal to or shorter than the leaves
    • the main stem is taller than the leaves
    Stem cross-section
    the main stem is roughly triangular in cross-section
    Stem spacing
    the stems grow close together in compact clusters or tufts

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

In New England

Distribution

Connecticut
absent
Maine
present
Massachusetts
absent
New Hampshire
present
Rhode Island
absent
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

New Hampshire
unrankable (S-rank: SU), Ind (code: Ind)
Vermont
extremely rare (S-rank: S1), endangered (code: E)

From Flora Novae Angliae dichotomous key

67.  Carex arcta Boott N

northern cluster sedge. Carex canescens L.  var. polystachya Boott • ME, NH, VT; also reported from MA by Toivonen (2002), but specimens are unknown. Wet-mesic to hydric forests, usually at least in part evergreen, sometimes bordering streams.

Native to North America?

Yes

Sometimes confused with

Carex brunnescens:
perigynia elliptic-ovate in outline, widest near the middle, and inflorescence composed of mostly 3-8 spikes where the lowest are usually separate (vs. C. arcta, with perigynia ovate in outline, widest near the base, and inflorescence composed of 5-15 spikes that are aggregated together).

Synonyms

  • Carex canescens L. var. polystachya Boott

Family

Cyperaceae

Genus

Carex