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Native Plant Trust: Go Botany Discover thousands of New England plants

Carex aquatilis — water sedge

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Facts

In some areas of the United States, water sedge is an important source of food for large waterfowl and a fair source of food for ungulates and small mammals.

Habitat

Fens (calcium-rich wetlands), marshes, 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
wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • Rhode Island
  • Vermont
Leaf blade width
2.5–8 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
  • the lowest spike on the plant is not borne on a peduncle
Top spike
the uppermost spike contains only staminate flowers
Perigynium hairs
the perigynium has no hairs
Perigynium length
2–3.3 mm
Leaf sheath color
  • the leaf sheath has no pink, red or purple tinting
  • 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 not divided at the tip into two teeth, or the teeth are very tiny
Show all characteristics

  • Flowers

    Bumps on fruit
    the perigynium surface has papillae on it
    Length of scale
    the scale is shorter than the perigynium
    Lowest spike length
    10–50 mm
    Lowest spike stalk length
    At least 0 mm
    Perigynium beak
    the perigynium has no beak, or an extremely short beak
    Perigynium beak length
    0.1–0.4 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
    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 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
    2–3.3 mm
    Perigynium nerve number
    0–4
    Perigynium nerve texture
    NA
    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
    1.25–1.75 mm
    Perigynium winged
    the perigynium has no wings
    Pollen- and seed-producing spikes
    some of the spikes produce perigynia
    Pollen-producing spike length
    10–50 mm
    Pollen-producing spike number
    1–4
    Scale awn
    The carpellate scale does not have an awn (it may have a short point)
    Scale awn texture
    NA
    Scale color
    • other
    • red-brown
    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
    • 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
    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 no folds or dimples
    Style persistence
    the style falls off 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 folded lengthwise, with one prominent midvien
    • 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 blade width
    2.5–8 mm
    Leaf bumps
    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
    • 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
    2.5–8 mm
    Lowest leaf sheath texture
    the leaf sheath feels smooth (it may have soft hairs)

  • Place

    Habitat
    wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • Rhode Island
    • Vermont
    Specific habitat
    • fens (calcium-rich wetlands)
    • marshes
    • meadows or fields
    • shores of rivers or lakes

  • Stem, shoot, branch

    Plant height
    20–150 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 singly or a few together (they may form diffuse colonies)

Wetland status

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

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
absent
Rhode Island
present
Vermont
present

Conservation status

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

Massachusetts
unranked (S-rank: SNR)
Vermont
rare (S-rank: S2)

ssp. altior

Rhode Island
extremely rare (S-rank: S1), state endangered (code: SE)

var. aquatilis

Connecticut
extremely rare (S-rank: S1), special concern (code: SC)
Massachusetts
unranked (S-rank: SNR)

var. substricta

Massachusetts
unranked (S-rank: SNR), #NAME? (code: #NAME?)

Subspecies and varieties

Our subspecies is Carex aquatilis Wahlenb. ssp. altior (Rydb.) Hultén.

From Flora Novae Angliae dichotomous key

130.  Carex aquatilis Wahlenb. ssp. altior (Rydb.) Hultén N

water sedge. Carex aquatilis Wahlenb. var. altior (Rydb.) Fern.; C. aquatilis Wahlenb. var. substricta Kükenth.; C. substricta (Kükenth.) Mackenzie • CT, MA, ME, RI, VT. Marshes, fens, river shores, graminoid meadows. This species was reported from NH by Magee and Ahles (1999); however, the voucher specimens are Carex haydenii and C. stricta (specimens at NHA!) and C. lenticularis (specimen at MASS!). Recent work by Dragon and Barrington (2009) showed that the traditional infraspecific taxonomy of C. aquatilis does not accurately reflect the phylogeny of this species (i.e., some of the varieties do not form distinct lineages). However, both molecular and morphological evidence support a division between North American and European populations (North American plants have thinner stems and broader carpellate scales than do European ones). Therefore, our plants are here treated as a separate subspecies from the European ssp. aquatilis. In New England, two morphological forms occur that show weak ecological differences. The common form, which occurs on relatively higher pH substrate, has pale carpellate scales with a narrow, red-brown margin and a broad, pale central band (the “ substricta” form). The less common form (primarily restricted to ME) has red-brown to black carpellate scales that have a narrow, pale margin and midrib (the “ aquatilis” form).

Native to North America?

Yes

Sometimes confused with

Carex lenticularis:
leaf blades 1.5-3.5 mm wide and perigynia with mostly 5-7 veins on eachs surface (vs. C. aquatilis, with leaf blades 2.5-8 mm wide and perigynia without veins or with 1-4 obscure veins on one surface).

Synonyms

  • Carex aquatilis Wahlenb. var. altior (Rydb.) Fern.
  • Carex aquatilis Wahlenb. var. substricta Kükenth.
  • Carex substricta (Kükenth.) Mackenzie

Family

Cyperaceae

Genus

Carex