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Carex backii — Back's sedge

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Facts

The lowest carpellate scales of Back's sedge are much longer than the perigynia, and bright green. The uppermost flowering spike is androgynous, with two or three staminate flowers, the rest being carpellate. This species is rare in southern New England.

Habitat

Cliffs, balds, or ledges, forests, woodlands

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
  • Vermont
stem leaf blade width
1.3–5.4 mm
Lowest bract sheath
NA
Spike on stalk
the lowest spike on the plant has a peduncle
Top spike
the uppermost spike contains both staminate and carpellate flowers, with the carpellate flowers located below, or intermixed with, the staminate flowers
Perigynium hairs
the perigynium has no hairs
Perigynium length
4.8–6.6 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 not divided at the tip into two teeth, or the teeth are very tiny
Show all characteristics

  • Flowers

    Anther length
    0.9–1.3 mm
    Bumps on fruit
    there are no papillae on the perigynium surface
    Length of scale
    the scale is nearly as long as, or longer than, the perigynium
    Perigynium beak
    the perigynium has a beak
    Perigynium beak length
    1.9–2.9 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
    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
    4.8–6.6 mm
    Perigynium nerve number
    At least 0
    Perigynium nerve texture
    • NA
    • the nerves on the perigynium are raised, even after drying the perigynium
    Perigynium nerves lower side
    At least 0
    Perigynium nerves upper side
    At least 0
    Perigynium orientation
    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 elliptic (widest near the middle and tapering at both ends)
    • the perigynium body is ovate (egg-shaped)
    Perigynium width
    1.9–3.2 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
    green
    Scale length
    15–70 mm
    Scale tip
    the carpellate scale tip is acute (has a sharp point)
    Spike on stalk
    the lowest spike on the plant has a peduncle
    Spike orientation
    the spikes are oriented vertically or pressed against the axis
    Spikes per stem
    • 1
    • 2-15
    Staminate scale tip
    the staminate scale tip is obtuse (has a blunt point)
    Stigma branching
    the stigmas have three branches
    Top spike
    the uppermost spike contains both staminate and carpellate flowers, with the carpellate flowers located below, or intermixed with, the staminate flowers

  • Fruits or seeds

    Achene dimples
    the achene has no folds or dimples
    Achene length
    2.5–3.2 mm
    Achene width
    1.6–2.3 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 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 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
    Lowest bract sheath
    NA
    Lowest leaf blade width
    1.3–5.4 mm
    Lowest leaf sheath texture
    the leaf sheath feels smooth (it may have soft hairs)
    stem leaf blade width
    1.3–5.4 mm

  • Place

    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Vermont
    Specific habitat
    • cliffs, balds, or ledges
    • forests
    • woodlands

  • Stem, shoot, branch

    Plant height
    1.4–25 cm
    Relative stem height
    the main stem is equal to or shorter than the leaves
    Spike internode length
    At least 0 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

Not classified

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
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.

Connecticut
extremely rare (S-rank: S1), endangered (code: E)
Maine
uncommon (S-rank: S3)
Massachusetts
extremely rare (S-rank: S1), endangered (code: E)
New Hampshire
extremely rare (S-rank: S1), endangered (code: E)
Vermont
uncommon (S-rank: S3)

From Flora Novae Angliae dichotomous key

154.  Carex backii Boott N

Back’s sedge. Carex backii Boott var. subrostrata (Bates) Dorn; C. durifolia Bailey • CT, MA, ME, NH, VT. Woodlands and forests, frequently on slopes or associated with cliff bases, exposed bedrock, and boulders, higher pH substrate to south, more general to north.

Native to North America?

Yes

Sometimes confused with

Carex willdenowii:
carpellate scales 1.6–2.2 mm wide, green with a hyaline margin 0.3–0.8 mm wide, and perigynia 1.2–1.7 mm wide (vs. C. backii, with carpellate scales mostly 2.5–6.5 mm wide, green throughout, and perigynia 1.9–3.2 mm wide).

Synonyms

  • Carex backii Boott var. subrostrata (Bates) Dorn
  • Carex durifolia Bailey

Family

Cyperaceae

Genus

Carex