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• Carex vacillans

Carex vacillans — swinging sedge

Facts

Swinging sedge is an unusual case of a stable, fertile hybrid between smooth black sedge (Carex nigra, a sedge of wet meadows) and chaffy sedge (C. paleacea, a salt marsh sedge). There is another stable hybrid sedge that shares one parent with swinging sedge, estuary sedge (C. recta). The two hybrid species are very similar to one another, and can only be distinguished with careful study. Swinging sedge is rare, and occurs in saline and brackish marshes and coastal shorelines in Maine and Massachusetts.

Habitat

Brackish or salt marshes and flats, intertidal, subtidal or open ocean, shores of rivers or lakes

Characteristics

• Flowers

  Bumps on fruit

  the perigynium surface has papillae on it

  Length of scale

  • the scale is nearly as long as, or longer than, the perigynium
  • the scale is shorter than the perigynium

  Lowest spike length

  28–50 mm

  Lowest spike stalk length

  6–17 mm

  Lowest spike width

  5–7 mm

  Perigynium beak

  the perigynium has a beak

  Perigynium beak length

  0.1–0.3 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 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 biconvex (convexly rounded on both sides, like a lens) in 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

  2.5–3.3 mm

  Perigynium nerve number

  4–10

  Perigynium nerve texture

  the nerves on the perigynium are raised, even after drying the perigynium

  Perigynium nerves lower side

  2–5

  Perigynium nerves upper side

  2–5

  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 obovate (egg-shaped, but with the widest point above the middle of the leaf blade)

  Perigynium width

  1.5–2.2 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 has an awn on it

  Scale awn texture

  the carpellate scale awn has tiny teeth

  Scale color

  • brown
  • purple to black

  Scale length

  2.5–5.5 mm

  Scale tip

  the carpellate scale tip is acuminate (tapered to a narrow point)

  Spike on stalk

  the lowest spike on the plant has a peduncle

  Spike orientation

  • the spikes are bent downwards or droop downwards
  • the spikes are oriented vertically or pressed against the axis

  Spikes per stem

  2-15

  Stigma branching

  the stigmas have two branches

  Top spike

  the uppermost spike contains only staminate flowers

• Fruits or seeds

  Achene dimples

  • the achene has a clear fold or dimple
  • the achene has no folds or dimples

  Style persistence

  the style falls off the mature achenes

• Leaves

  Leaf arrangement

  the leaves are all produced from the base of the plant

  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
  • 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

  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

  2.8–4 mm

  Lowest leaf sheath texture

  the leaf sheath feels smooth (it may have soft hairs)

  stem leaf blade width

  2.8–4 mm

• Place

  Habitat

  • terrestrial
  • wetlands

  New England state

  • Maine
  • Massachusetts

  Specific habitat

  • brackish or salt marshes and flats
  • intertidal, subtidal or open ocean
  • shores of rivers or lakes

• Stem, shoot, branch

  Plant height

  15–60 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

Not classified

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae