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Carex bullata — button sedge

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Facts

Button sedge is mainly a species of acidic bogs and meadows along the coastal plain. It is listed as endangered in New Hampshire.

Habitat

Bogs, fens, meadows and fields, 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
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
stem leaf blade width
1.8–5 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
Top spike
the uppermost spike contains only staminate flowers
Perigynium hairs
the perigynium has no hairs
Perigynium length
5.9–10.2 mm
Leaf sheath color
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
    there are no papillae on the perigynium surface
    Inflorescence length
    80–300 mm
    Length of scale
    the scale is shorter than the perigynium
    Lowest spike length
    15–40 mm
    Lowest spike width
    15–20 mm
    Perigynium beak
    the perigynium has a beak
    Perigynium beak length
    2.4–4.8 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
    0.5–1.4 mm
    Perigynium color
    • brown
    • green
    Perigynium cross-section
    • the perigynium is relatively round in cross-section
    • the perigynium is trigonous (triangular) in cross-section
    Perigynium hairs
    the perigynium has no hairs
    Perigynium length
    5.9–10.2 mm
    Perigynium nerve number
    9–12
    Perigynium nerve texture
    the nerves on the perigynium are raised, even after drying the perigynium
    Perigynium nerves lower side
    4–6
    Perigynium nerves upper side
    4–6
    Perigynium orientation
    • the perigynia are angled outwards
    • the perigynia are oriented vertically or pressed against the axis or adjacent perigynia
    Perigynium puffy
    the perigynium is inflated (there is space between the perigynium and the achene)
    Perigynium shape
    • the perigynium body is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    • the perigynium body is ovate (egg-shaped)
    Perigynium width
    2.4–3.3 mm
    Perigynium winged
    the perigynium has no wings
    Pollen- and seed-producing spikes
    some of the spikes produce perigynia
    Pollen-producing spike number
    1–3
    Scale awn
    The carpellate scale does not have an awn (it may have a short point)
    Scale awn texture
    NA
    Scale color
    • brown
    • green
    Scale length
    3.5–5.2 mm
    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 has a peduncle
    Spike orientation
    • the spikes are angled outwards, or arched over
    • the spikes are oriented vertically or pressed against the axis
    Spikes per stem
    2-15
    Stigma branching
    the stigmas have three 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 stays on the mature achenes

  • Growth form

    Rhizomes
    there are long rhizomes present

  • Leaves

    Leaf arrangement
    the leaves are mostly produced higher up on the plant
    Leaf blade cross-section
    the leaf blade is flat or M-shaped, with two prominent side-veins
    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 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
    1.8–5 mm
    Lowest leaf sheath texture
    the leaf sheath feels smooth (it may have soft hairs)
    stem leaf blade width
    1.8–5 mm

  • Place

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

  • Stem, shoot, branch

    Plant height
    30–85 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
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
absent

Conservation status

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

Maine
rare (S-rank: S2), special concern (code: SC)
Massachusetts
widespread (S-rank: S5)
New Hampshire
extremely rare (S-rank: S1), endangered (code: E)

From Flora Novae Angliae dichotomous key

179.  Carex bullata Schkuhr ex Willd. N

button sedge. CT, MA, ME, NH, RI. Open fens, bogs, meadows, and lakeshores.

179×190. Carex bullata × Carex utriculata → Carex ×‌olneyi Boott is a rare hybrid known from RI. The hybrid can be recognized by its general similarity to Carex bullata, but the perigynia beaks are shorter (1.9–2.6 mm long) and vary in their presence of scabrules (some beak margins are smooth, some have a few scabrules, others have abundant scabrules). There are additional specimens determined to be this hybrid (including collections from CT, MA, and NH). However, those seen by me from CT and NH are true C. bullata, and most of those from MA are also true C. bullata. More study is needed to determine the range of this nothospecies in New England.

Native to North America?

Yes

Sometimes confused with

Carex vesicaria:
perigynium beak mostly 1.2-2.7 mm long, smooth (vs. C. bullata, with the perigynium beak mostly 2.4-4.2 mm long, scabrous in the apical portion).

Family

Cyperaceae

Genus

Carex