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

Cyperus odoratus — rusty flatsedge

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Facts

Rusty flatsedge is a very rare plant that is known from Connecticut, Massachusetts, New Hampshire, Rhode Island and Vermont, although in some of these states it may no longer be present. It inhabits shorelines, tidal marshes, and wet or muddy sites including meadows throughout the tropics and warm temperate regions of the world. It also goes by the common name of "fragrant flatsedge." Yuman native americans have used the seeds for food.

Habitat

Brackish or salt marshes and flats, 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
  • aquatic
  • wetlands
New England state
  • Connecticut
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Stem shape in cross-section
the stem is roughly triangular in cross-section
Leaf blade width
4–12 mm
Leaf blade cross-section
the leaf blade is flat or rolled in at the edges
Inflorescence position
the inflorescence is at the tip of the plant
Inflorescence branching
  • the inflorescence is branched
  • the inflorescence is on one or more stems with no branches
Fruit type (general)
the fruit is like a seed, and surrounded by scales
Fruit length
1–1.9 mm
Leaf position on plant
the attachment points of all the leaves are at or near the base of the plant
Perianth composition
there is no perianth on the plant
Fruit cross-section
the fruit is triangular to terete (circular) in cross-section
Show all characteristics

  • Flowers

    Anther length
    0.2–0.7 mm
    Floral bristle color
    NA
    Floral bristle number
    0
    Floral bristle relative length
    NA
    Floral bristles
    NA
    Floral scale hairs
    there are no hairs on the floral scales
    Floral scale length
    1.5–3.2 mm
    Floral scale nerves
    7 or more
    Floral scale shape
    • the floral scales are elliptic (widest in the middle and tapering toward each end)
    • the floral scales are ovate (roughly egg-shaped)
    Floral scale translucent
    the floral scales are opaque
    Flower number per cluster
    • 5-20
    • more than 20
    Inflorescence bract number
    there are two to five bracts per inflorescence
    Inflorescence bract position (Sparganium)
    NA
    Inflorescence bracts
    there are at least two bracts, and they are either flat or folded or rolled in at the edges
    Inflorescence branching
    • the inflorescence is branched
    • the inflorescence is on one or more stems with no branches
    Inflorescence crowding
    the inflorescence is crowded together in one tight cluster
    Inflorescence position
    the inflorescence is at the tip of the plant
    Inflorescence shape
    the aggregations within the inflorescence are at least somewhat flattened in cross-section
    Inflorescence type
    there are two or more flowers, spikes or flower clusters on a branched inflorescence
    Perianth composition
    there is no perianth on the plant
    Stamen number
    • 2
    • 3
    Stigma number
    3
    Style division
    the top two thirds of the style is divided
    floral bristle barbs
    NA
    plantlets budding at flower bases
    no

  • Fruits or seeds

    Achene surface texture
    the achene has very tiny pits or depressions on it
    Achene tubercle relative width
    NA
    Achene tubercle width
    0 mm
    Capsule relative length
    NA
    Fruit cross-section
    the fruit is triangular to terete (circular) in cross-section
    Fruit length
    1–1.9 mm
    Fruit type (general)
    the fruit is like a seed, and surrounded by scales
    Fruit type (specific)
    the fruit is an achene (dry, seed-like fruit) without a tubercle (a swelling or projection, usually of a different color or texture)
    Locules in capsule
    NA
    Seed length
    0 mm
    Seed tail relative length
    0 mm
    Seed tails
    NA
    Tubercle height
    0 mm

  • Growth form

    Lifespan
    • the plant lives more than two years
    • the plant lives only a single year or less
    Underground organs
    there are only slender roots on the plant

  • Leaves

    Auricle length
    0 mm
    Auricle texture
    NA
    Auricles
    there are no auricles on the leaf sheath
    Leaf blade cross-section
    the leaf blade is flat or rolled in at the edges
    Leaf blade length
    50–600 mm
    Leaf blade width
    4–12 mm
    Leaf form
    all the leaves hold their form out of water
    Leaf position on plant
    the attachment points of all the leaves are at or near the base of the plant
    Leaf septa
    the leaf blades do not have transverse septa
    Leaf sheath hairs
    the leaf sheathes are without hairs
    Pedicel length (Typha)
    0 mm
    Stem leaf blade ligules
    there are no ligules at the leaf blade bases
    Stem leaf blades
    there are fully-developed leaves with leaf blades on the main stem
    Width of seed-producing inflorescence
    8–35 mm

  • Place

    Habitat
    • aquatic
    • wetlands
    New England state
    • Connecticut
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • brackish or salt marshes and flats
    • meadows or fields
    • shores of rivers or lakes

  • Stem, shoot, branch

    Plant height
    4–130 cm
    Stem shape in cross-section
    the stem is roughly triangular in cross-section
    Stem texture near tip
    the stem feels smooth near the tip

Wetland status

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

In New England

Distribution

Connecticut
present
Maine
absent
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.

Connecticut
fairly widespread (S-rank: S4)
Massachusetts
uncommon to fairly widespread (S-rank: S3S4)
New Hampshire
extremely rare (S-rank: S1), endangered (code: E)
Rhode Island
extremely rare (S-rank: S1), concern (uncertain) (code: C*)
Vermont
extremely rare (S-rank: S1)

From Flora Novae Angliae dichotomous key

16.  Cyperus odoratus L. NC

rusty flatsedge. Cyperus engelmannii Steud.; C. ferax L.C. Rich; C. ferruginescens Boeckl.; Torulinium odoratum (L.) S. Hooper • CT, MA, NH, RI, VT. Shorelines, tidal marshes, wet sand, muddy depressions, meadows. Immature specimens of Cyperus odoratus can be confused with first-year flowering forms of C. strigosus (the latter species is much more common in New England). In addition to scale length, the red-brown spikelets of C. odoratus can be helpful to separate specimens of C. strigosus (which have yellow-brown to brown spikelets).

Native to North America?

Yes

Sometimes confused with

Cyperus esculentus:
anthers 1-1.6 mm long and plants with long, slender rhizomes ending in tubers (vs. C. odoratus, with anthers 0.2-0.7 mm long and plants annual from slender roots).
Cyperus strigosus:
plants usually perennial, floral scales mostly 3.2-4.5 mm long, and achenes broad-linear to narrow-oblong (vs. C. odoratus, with plants annual, floral scales mostly 2-2.8 mm long, and achenes elliptic to narrow-obovate in outline).

Synonyms

  • Cyperus engelmannii Steud.
  • Cyperus ferax L.C. Rich
  • Cyperus ferruginescens Boeckl.
  • Torulinium odoratum (L.) S. Hooper

Family

Cyperaceae

Genus

Cyperus