Carex flava L.

yellow-green sedge

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

Yellow-green sedge may get its name from the perigynia (coverings of the seeds), which have a yellow body and a green or yellow beak. It is an obligate wetland species that prefers high-pH sites.

Habitat

Meadows and fields, ridges or ledges, shores of rivers or lakes

Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
stem leaf blade width
1.6–5.8 mm
Lowest bract sheath
  • the lowest bract has a sheath longer than four millimeters
  • 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 both staminate and carpellate flowers, with the carpellate flowers located below, or intermixed with, the staminate flowers
  • the uppermost spike contains only staminate flowers
Perigynium hairs
  • the perigynium has no hairs
  • the perigynium is hairy
Perigynium length
4–6.3 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 divided at the top into two teeth
Show All Characteristics
  • Flowers
    Anther length
    1–2.1 mm
    Bumps on fruit
    there are no papillae on the perigynium surface
    Length of scale
    the scale is shorter than the perigynium
    Lowest spike length
    8–22 mm
    Lowest spike stalk length
    At least 0 mm
    Lowest spike width
    7.5–12.7 mm
    Perigynium beak
    the perigynium has a beak
    Perigynium beak length
    1.3–2.7 mm
    Perigynium beak orientation
    the beak of the perigynium is curved, or angled out from the perigynium
    Perigynium beak 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 0.5 mm
    Perigynium color
    yellow
    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
    • the perigynium is hairy
    Perigynium length
    4–6.3 mm
    Perigynium nerve number
    At least 10
    Perigynium nerve texture
    the nerves on the perigynium are raised, even after drying the perigynium
    Perigynium nerves lower side
    At least 5
    Perigynium nerves upper side
    At least 5
    Perigynium orientation
    the perigynia are curved or bent downwards or backwards along the axis
    Perigynium puffy
    the perigynium is inflated (there is space between the perigynium and the achene)
    Perigynium shape
    • the perigynium body is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    • the perigynium body is ovate (egg-shaped)
    Perigynium width
    1–1.9 mm
    Perigynium winged
    the perigynium has no wings
    Pollen- and seed-producing spikes
    some of the spikes produce perigynia
    Pollen-producing spike length
    9–22 mm
    Pollen-producing spike number
    1–2
    Pollen-producing spike peduncle length
    0.4–9 mm
    Pollen-producing spike width
    1.1–3 mm
    Scale awn
    The carpellate scale does not have an awn (it may have a short point)
    Scale awn texture
    • NA
    • the carpellate scale awn does not have teeth (it may or may not have hairs)
    Scale color
    red-brown
    Scale length
    2.3–3.9 mm
    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 angled outwards, or arched over
    • the spikes are oriented vertically or pressed against the axis
    Spikes per stem
    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
    • the uppermost spike contains only staminate flowers
  • Fruits or seeds
    Achene dimples
    the achene has no folds or dimples
    Achene length
    1.3–1.7 mm
    Achene width
    0.9–1.2 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 length to width ratio
    31–52
    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
    • the lowest bract has a sheath longer than four millimeters
    • the lowest bract has no sheath (or a very short sheath up to four millimeters in length)
    Lowest leaf blade width
    1.6–5.8 mm
    Lowest leaf sheath texture
    the leaf sheath feels smooth (it may have soft hairs)
    stem leaf blade width
    1.6–5.8 mm
  • Place
    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • meadows or fields
    • ridges or ledges
    • shores of rivers or lakes
  • Stem, shoot, branch
    Plant height
    10–75 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 close together in compact clusters or tufts

Wetland Status

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

New England Distribution and Conservation Status

Distribution

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

Conservation Status

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

Massachusetts
fairly widespread (S-rank: S4)
Vermont
widespread (S-rank: S5)

Native to North America?

Yes

Sometimes Confused With

Carex cryptolepis:
perigynia 3.5-4.8 mm long, of similar color with the yellow-green carpellate scales, with a smooth beak offset 13-48 degrees from the body (vs. C. flava, with perigynia 4-6.3 mm long, contrasting in color with the red-brown carpellate scales, with a scabrous beak offset mostly 26-72 degrees from the body).

Synonyms

  • Carex flava var. fertilis Peck
  • Carex flava var. gaspensis Fern.
  • Carex laxior (Kükenth.) Mackenzie

Family

Cyperaceae

Genus

Carex

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Information from Dichotomous Key of Flora Novae Angliae

27.  Carex flava L. N

yellow-green sedge. Carex flava L. var. fertilis Peck; C. flava L. var. gaspensis Fern.; 
 C. laxior (Kükenth.) Mackenzie • CT, MA, ME, NH, RI, VT. Wet meadows, shorelines, and 
seepy ledges; calciphile.

27×28. Carex flava × Carex viridula Carex  ×‌ruedtii Kneuck. is a rare sedge hybrid in New England known 
from MA, ME, NH. It is recognized by its perigynia that are mostly 3.1–4 mm long with 
a smooth or sparsely serrulate, essentially straight beak, carpellate scales that are brown and contrast with the green perigynia, and upper leaves with ligules (lacking ligules in C. viridula).