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• Carex Group 1
• Section Macrocephalae
• Carex kobomugi

Carex kobomugi — Japanese sedge

Facts

Japanese sedge is native to East Asia and introduced on sandy beaches in Massachusetts and Rhode Island. Although it is prohibited in Massachusetts, clones of Japanese sedge are being used for dune stabilization elsewhere, so the range of this invasive species will likely expand.

Habitat

Anthropogenic (man-made or disturbed habitats), coastal beaches (sea beaches)

Characteristics

• Flowers

  Anther length

  4–6.5 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

  Lowest spike length

  30–60 mm

  Lowest spike stalk length

  0 mm

  Lowest spike width

  20–40 mm

  Perigynium beak

  the perigynium has a beak

  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

  Perigynium beak teeth

  the perigynium beak is divided at the top into two teeth

  Perigynium beak teeth length

  At least 0.4 mm

  Perigynium color

  • brown
  • tan

  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

  10–14 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 shape

  the perigynium body is ovate (egg-shaped)

  Perigynium winged

  the perigynium has wings on it

  Pollen- and seed-producing spikes

  • all the spikes produce only pollen
  • some of the spikes produce perigynia

  Pollen-producing spike length

  30–40 mm

  Pollen-producing spike number

  0–1

  Pollen-producing spike peduncle length

  0 mm

  Pollen-producing spike width

  10–20 mm

  Scale awn

  the carpellate scale has an awn on it

  Scale color

  • green
  • other

  Scale tip

  the carpellate scale tip is acuminate (tapered to a narrow 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

  more than 15

  Stigma branching

  the stigmas have three branches

  Top spike

  • entirely carpellate
  • the uppermost spike contains both staminate and carpellate flowers, with the carpellate flowers located below, or intermixed with, the staminate flowers
  • the uppermost spike contains only staminate flowers

• Fruits or seeds

  Achene dimples

  the achene has no folds or dimples

  Achene length

  4–7 mm

  Achene width

  1.5–2.5 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

  Leaf blade texture

  the leaf blade is smooth and hairless, or rough and sandpapery

  Leaf blade width

  4–8 mm

  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

  the lowest bract has no sheath (or a very short sheath up to four millimeters in length)

  Lowest leaf blade width

  4–8 mm

  Lowest leaf sheath texture

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

• Place

  Habitat

  terrestrial

  New England state

  • Massachusetts
  • Rhode Island

  Specific habitat

  • man-made or disturbed habitats
  • sea beaches

• Stem, shoot, branch

  Plant height

  10–30 cm

  Relative stem height

  the main stem is equal to or shorter 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