• You are here:
• Dichotomous Key
• Cyperaceae
• Cyperus
• Cyperus filicinus

Cyperus filicinus — fern flatsedge

Facts

Fern flatsedge grows along the east coast on shorelines, the upper edges of salt and brackish marshes, and intertidal zones. It occurs along the entire eastern seaboard south to Louisiana, and in ditches in the interior US (Illinois). This annual plant produces widely spreading spikes that give rise to fruits in summer.

Habitat

Brackish or salt marshes and flats, shores of rivers or lakes, wetland margins (edges of wetlands)

Characteristics

• Flowers

  Anther length

  0.5 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

  2.5–3.5 mm

  Floral scale nerves

  2-5

  Floral scale shape

  • the floral scales are oblong (rectangular but with rounded ends)
  • the floral scales are ovate (roughly egg-shaped)

  Floral scale translucent

  the floral scales are opaque

  Flower number per cluster

  5-20

  Inflorescence bract angle

  the bracts are vertical or angled only slightly outwards

  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 at least somewhat spread out, with at least one branch coming from the main stem

  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

  Stigma number

  2

  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 beak length

  0 mm

  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 lenticular (lens-shaped) in cross-section

  Fruit length

  1.2–1.6 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 only a single year or less

  Underground organs

  the plant has a rhizome (a horizontal underground stem with roots growing from it)

• 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

  100–300 mm

  Leaf blade width

  1–3 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

  10–22 mm

• Place

  Habitat

  • aquatic
  • wetlands

  New England state

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

  Specific habitat

  • brackish or salt marshes and flats
  • edges of wetlands
  • shores of rivers or lakes

• Stem, shoot, branch

  Plant height

  5–50 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)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae