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Carex sterilis — dioecious sedge

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Facts

Dioecious sedge is nearly always dioecious (having male and female reproductive structures on separate plants). This is a species of conservation concern chiefly because of the rarity of the calcareous fens in which it grows.

Habitat

Fens, meadows and fields, shores of rivers or lakes, 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
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • Rhode Island
  • Vermont
stem leaf blade width
1.2–2.6 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
  • entirely carpellate
  • the uppermost spike contains only staminate flowers
Perigynium hairs
the perigynium has no hairs
Perigynium length
2.1–3.8 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
Show all characteristics

  • Flowers

    Anther length
    1–2.35 mm
    Bumps on fruit
    there are no papillae on the perigynium surface
    Distance between perigynia
    3.8–15.5 mm
    Length of scale
    the scale is nearly as long as, or longer than, the perigynium
    Lowest spike length
    3–13.5 mm
    Lowest spike stalk length
    0 mm
    Lowest spike width
    4.5–7.2 mm
    Perigynium beak
    the perigynium has a beak
    Perigynium beak length
    0.65–1.6 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 beak teeth length
    0.15–0.5 mm
    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
    2.1–3.8 mm
    Perigynium nerve number
    5–22
    Perigynium nerve texture
    the nerves on the perigynium are raised, even after drying the perigynium
    Perigynium nerves lower side
    5–12
    Perigynium nerves upper side
    0–10
    Perigynium orientation
    • the perigynia are angled outwards
    • the perigynia are curved or bent downwards or backwards along the axis
    Perigynium shape
    • the perigynium body is ovate (egg-shaped)
    • the perigynium body is triangular, widest near the base
    Perigynium width
    1.2–2.2 mm
    Perigynium winged
    the perigynium has no wings
    Pollen- and seed-producing spikes
    • all the spikes produce only pollen
    • some of the spikes produce perigynia
    Pollen-producing spike length
    3.5–13.7 mm
    Pollen-producing spike number
    0–1
    Pollen-producing spike peduncle length
    At least 0 mm
    Pollen-producing spike width
    1.2–2.6 mm
    Scale awn
    The carpellate scale does not have an awn (it may have a short point)
    Scale awn texture
    NA
    Scale color
    red-brown
    Scale length
    1.8–2.9 mm
    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 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
    • entirely carpellate
    • the uppermost spike contains only staminate flowers

  • Fruits or seeds

    Achene dimples
    the achene has no folds or dimples
    Achene length
    1–1.7 mm
    Achene width
    0.9–1.3 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 mostly produced higher up on the plant
    Leaf blade cross-section
    The leaf blade is folded lengthwise, with one prominent midvien
    Leaf blade length to width ratio
    63–96
    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 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
    Ligule length
    0.3–1.7 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
    1.2–2.6 mm
    Lowest leaf sheath texture
    the leaf sheath feels smooth (it may have soft hairs)
    stem leaf blade width
    1.2–2.6 mm

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • Rhode Island
    • Vermont
    Specific habitat
    • fens
    • meadows or fields
    • shores of rivers or lakes
    • swamps

  • Stem, shoot, branch

    Plant height
    10–75 cm
    Relative stem height
    the main stem is taller than the leaves
    Spike internode length
    9–40 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.

Connecticut
uncommon (S-rank: S3), special concern (code: SC)
Maine
uncommon (S-rank: S3), special concern (code: SC)
Massachusetts
rare (S-rank: S2), threatened (code: T)
Rhode Island
historical (S-rank: SH), state historical (code: SH)
Vermont
extremely rare (S-rank: S1)

From Flora Novae Angliae dichotomous key

175.  Carex sterilis Willd. NC

dioecious sedge. Carex elachycarpa Fern.; C. muricata L. var. sterilis (Fern.) Gleason; Kobresia elachycarpa (Fern.) Fern. • CT, MA, ME, RI, VT. Fens, river shore seeps, and wet meadows.

Native to North America?

Yes

Sometimes confused with

Carex echinata:
plants monoecious, at the last the uppermost spike clearly bisexual, and anthers 0.8-1.6 mm long (vs. C. sterilis, the plants subdioecious, the spikes all or nearly all of a single sex on each stem, and anthers mostly 1.2-2.2 mm long).
Carex interior:
plants monoecious, at the last the uppermost spike clearly bisexual, and anthers 0.6-1.4 mm long (vs. C. sterilis, the plants subdioecious, the spikes all or nearly all of a single sex on each stem, and anthers mostly 1.2-2.2 mm long).

Synonyms

  • Carex elachycarpa Fern.
  • Carex muricata L. var. sterilis (Fern.) Gleason
  • Kobresia elachycarpa (Fern.) Fern.

Family

Cyperaceae

Genus

Carex