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Carex trisperma — three-seeded sedge

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Facts

In spite of its name, three-seeded sedge may have two to five perigynia in the terminal spike. The species has a circumpolar distribution and inhabits swamps, fens and bogs, usually in peaty soils and under shade.

Habitat

Bogs, fens, forests, swamps

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
stem leaf blade width
0.8–1.9 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
2.5–3.7 mm
Leaf sheath color
the leaf sheath has no pink, red or purple tinting
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
  • 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
    • there are no papillae on the perigynium surface
    Inflorescence length
    14–55 mm
    Length of scale
    • the scale is nearly as long as, or longer than, the perigynium
    • the scale is shorter than the perigynium
    Lowest spike stalk length
    0 mm
    Perigynium beak
    the perigynium has a beak
    Perigynium beak length
    0–0.5 mm
    Perigynium beak orientation
    the beak of the perigynium is straight, and in line with the perigynium
    Perigynium beak serrations
    • the perigynium beak has no serrations
    • the perigynium beak has tiny serrations along the edges
    Perigynium beak teeth
    • the perigynium beak is divided at the top into two teeth
    • the perigynium beak is not divided at the tip into two teeth, or the teeth are very tiny
    Perigynium beak teeth length
    At least 0 mm
    Perigynium color
    • brown
    • green
    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
    2.5–3.7 mm
    Perigynium nerve texture
    the nerves on the perigynium are raised, even after drying the perigynium
    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 ovate (egg-shaped)
    Perigynium width
    1.5–2 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
    white or translucent
    Scale tip
    the carpellate scale tip is acute (has a sharp point)
    Spike on stalk
    the lowest spike on the plant is not borne on a peduncle
    Spike orientation
    the spikes are bent downwards or droop downwards
    Spikes per stem
    2-15
    Staminate scale tip
    the staminate scale tip is acuminate (tapered to a narrow 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
    1.75–2 mm
    Achene width
    1.25–1.5 mm
    Style persistence
    the style falls off the mature achenes

  • Growth form

    Rhizomes
    there are long rhizomes present

  • 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
    • the leaf blade is flat or M-shaped, with two prominent side-veins
    Leaf blade length to width ratio
    100–200
    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
    Leaf sheath dots
    there are white dots on the green 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
    Ligule length
    0.5–1.9 mm
    Lowest bract sheath
    the lowest bract has no sheath (or a very short sheath up to four millimeters in length)
    Lowest leaf blade width
    0.8–1.9 mm
    Lowest leaf sheath texture
    the leaf sheath feels smooth (it may have soft hairs)
    stem leaf blade width
    0.8–1.9 mm

  • Place

    Habitat
    wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • bogs
    • fens
    • forests
    • swamps

  • Stem, shoot, branch

    Plant height
    20–70 cm
    Relative stem height
    the main stem is taller than the leaves
    Spike internode length
    20–40 mm
    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
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.

Maine
unranked (S-rank: SNR)
Massachusetts
fairly widespread (S-rank: S4)

From Flora Novae Angliae dichotomous key

73.  Carex trisperma Dewey N

three-seeded sedge. CT, MA, ME, NH, RI, VT. Hydric, usually peaty soils of bogs, fens, and evergreen swamps, usually in shaded situations.

72×73. Carex tenuiflora × Carex trisperma → Carex ×‌trichina Fern. is a rare sedge hybrid known from ME. Characteristics that distinguish this plant are its short-beaked perigynia and less congested inflorescence (compared with C. tenuiflora).

Native to North America?

Yes

Sometimes confused with

Carex billingsii:
leaf blades mostly 0.3-0.5 mm wide, involute, and ligules mostly 0.3-0.8 mm long (vs. C. trisperma, with leaf blades mostly 1-1.9 mm wide, flat to partially folded, and ligules 0.5-1.9 mm long).

Family

Cyperaceae

Genus

Carex