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• Dichotomous Key
• Cyperaceae
• Carex
• Carex Group 6
• Section Lupulinae
• Carex lupulina

Carex lupulina — hop sedge

Facts

Hop sedge inhabits the eastern half of North America, where it is found in marshy lakeshores, swamp openings and grassy marshes. Its achenes provide food for waterfowl.

Habitat

Marshes, shores of rivers or lakes, swamps

Characteristics

• Flowers

  Anther length

  3–5.5 mm

  Bumps on fruit

  there are no papillae on the perigynium surface

  Inflorescence length

  40–400 mm

  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

  15–65 mm

  Lowest spike stalk length

  5–200 mm

  Lowest spike width

  13–30 mm

  Perigynium beak

  the perigynium has a beak

  Perigynium beak length

  6–10 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 divided at the top into two teeth

  Perigynium beak teeth length

  Up to 1 mm

  Perigynium color

  green

  Perigynium cross-section

  the perigynium is relatively round in cross-section

  Perigynium hairs

  the perigynium has no hairs

  Perigynium length

  11–19 mm

  Perigynium nerve number

  13–22

  Perigynium nerve texture

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

  Perigynium nerves lower side

  6–11

  Perigynium nerves upper side

  6–11

  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 lanceolate (lance-shaped; widest below the middle and tapering at both ends)
  • the perigynium body is ovate (egg-shaped)

  Perigynium width

  3–6 mm

  Perigynium winged

  the perigynium has no wings

  Pollen- and seed-producing spikes

  some of the spikes produce perigynia

  Pollen-producing spike length

  15–85 mm

  Pollen-producing spike number

  1–2

  Pollen-producing spike peduncle length

  5–70 mm

  Pollen-producing spike width

  1–5 mm

  Scale awn

  the carpellate scale has an awn on it

  Scale awn texture

  the carpellate scale awn has tiny teeth

  Scale color

  • green
  • white or translucent

  Scale length

  6–15 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

  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

  Achene length

  3–4.5 mm

  Achene width

  1.7–2.8 mm

  Style persistence

  the style stays on 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 length to width ratio

  38–42

  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
  • 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

  Ligule length

  3.5–18 mm

  Lowest bract sheath

  the lowest bract has a sheath longer than four millimeters

  Lowest leaf blade width

  4–15 mm

  Lowest leaf sheath texture

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

  stem leaf blade width

  4–15 mm

• Place

  Habitat

  wetlands

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont

  Specific habitat

  • marshes
  • shores of rivers or lakes
  • swamps

• Stem, shoot, branch

  Plant height

  20–130 cm

  Relative stem height

  • the main stem is equal to or shorter than the leaves
  • the main stem is taller than the leaves

  Spike internode length

  10–200 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
  • the stems grow singly or a few together (they may form diffuse colonies)

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae