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Carex nigra — smooth black sedge

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Facts

Smooth black sedge is one of the more distinctive species, with dramatic purple-brown to black scales only partially covering the perigynia (sacs surrounding achenes), sometimes giving the spikes a checkered appearance.

Habitat

Anthropogenic (man-made or disturbed habitats), meadows and fields

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
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf blade width
2–4.5 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 has a peduncle
  • the lowest spike on the plant is not borne on a peduncle
Top spike
the uppermost spike contains only staminate flowers
Perigynium hairs
the perigynium has no hairs
Perigynium length
2–3.7 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 not divided at the tip into two teeth, or the teeth are very tiny
Show all characteristics

  • Flowers

    Bumps on fruit
    the perigynium surface has papillae on it
    Length of scale
    the scale is shorter than the perigynium
    Lowest spike length
    12–42 mm
    Lowest spike stalk length
    At least 0 mm
    Lowest spike width
    3–5 mm
    Perigynium beak
    the perigynium has a beak
    Perigynium beak length
    0.1–0.2 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 not divided at the tip into two teeth, or the teeth are very tiny
    Perigynium beak teeth length
    0 mm
    Perigynium color
    tan
    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
    2–3.7 mm
    Perigynium nerve number
    6–18
    Perigynium nerve texture
    the nerves on the perigynium are raised, even after drying the perigynium
    Perigynium nerves lower side
    3–9
    Perigynium nerves upper side
    3–9
    Perigynium orientation
    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 elliptic (widest near the middle and tapering at both ends)
    • the perigynium body is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    Perigynium width
    1.1–2.1 mm
    Perigynium winged
    the perigynium has no wings
    Pollen- and seed-producing spikes
    some of the spikes produce perigynia
    Pollen-producing spike number
    1–2
    Scale awn
    The carpellate scale does not have an awn (it may have a short point)
    Scale awn texture
    NA
    Scale color
    • brown
    • purple to black
    Scale tip
    the carpellate scale tip is obtuse (has a blunt point)
    Spike on stalk
    • the lowest spike on the plant has a peduncle
    • 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)
    Stigma branching
    the stigmas have two branches
    Top spike
    the uppermost spike contains only staminate flowers

  • Fruits or seeds

    Achene dimples
    the achene has no folds or dimples
    Style persistence
    the style falls off the mature achenes

  • Growth form

    Rhizomes
    • there are long rhizomes present
    • 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 folded lengthwise, with one prominent midvien
    Leaf blade texture
    the leaf blade is smooth and hairless, or rough and sandpapery
    Leaf blade width
    2–4.5 mm
    Leaf bumps
    the upper surface of the leaf blade has papillae on it
    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 no dots on 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
    2–4.5 mm
    Lowest leaf sheath texture
    the leaf sheath feels smooth (it may have soft hairs)

  • Place

    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • man-made or disturbed habitats
    • meadows or fields

  • Stem, shoot, branch

    Plant height
    10–110 cm
    Relative stem height
    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 singly or a few together (they may form diffuse colonies)

Wetland status

Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)

In New England

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

From Flora Novae Angliae dichotomous key

138.  Carex nigra (L.) Reichard N

smooth black sedge. Carex acuta L. var. nigra L.; C. nigra (L.) Reichard var. strictiformis 
 (Bailey) Fern. • CT, MA, ME, NH, RI, VT. Lawns, low fields and meadows, ditches, usually within 
the coastal region.

135×138. Carex haydenii × Carex nigra → This very rare sedge hybrid is known from MA. It is most similar to Carex nigra due to the dark carpellate scales and perigynia that are usually suffused with dark 
red-brown. However, the carpellate scales are acute to acuminate and usually at least reach the base of the perigynium beak varying to sometimes shortly surpassing the 
beak (vs. carpellate scales that are rounded to obtuse (rarely acute) at the apex that usually do not reach the base of the beak). The leaves of the hybrid are generally shorter and mostly don’t reach the base of the inflorescence (vs. commonly reaching the inflorescence to equaling the height of the plant).

Native to North America?

Yes

Synonyms

  • Carex acuta L. var. nigra L.
  • Carex nigra var. strictiformis (Bailey) Fern.

Family

Cyperaceae

Genus

Carex