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Eleocharis tenuis — slender spikesedge

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Facts

Slender spikesedge is found in lake and stream shores and other wet areas. There are two varieties in New England, one being much more common than the other. As its name suggests, it is an unusually slender-stemmed species.

Habitat

Anthropogenic (man-made or disturbed habitats), 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
  • New Hampshire
  • Rhode Island
  • Vermont
Stem shape in cross-section
  • the stem is roughly quadrangular in cross-section
  • the stem is round or oval in cross-section
Leaf blade width
0 mm
Leaf blade cross-section
NA
Inflorescence position
the inflorescence is at the tip of the plant
Inflorescence branching
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
0.6–0.9 mm
Leaf position on plant
the attachment points of all the leaves are at or near the base of the plant
Perianth composition
  • there are bristles attached at the base of the achene
  • 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 color (dry)
    the anthers range in color from white to tan or yellow to yellow-brown
    Anther length
    0.8–1.8 mm
    Floral bristle color
    the bristles are pale brown to brown
    Floral bristle number
    1-4
    Floral bristle relative length
    • the bristles are between one tenth as long as the achene, and equal in length to the achene
    • there are no bristles, or they are very tiny (less than one tenth as long as the achene)
    Floral bristles
    the bristles are straight or slightly curved
    Floral scale hairs
    there are no hairs on the floral scales
    Floral scale length
    1.5–2.5 mm
    Floral scale nerves
    1
    Floral scale shape
    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 angle
    NA
    Inflorescence bract number
    NA
    Inflorescence bract position (Sparganium)
    NA
    Inflorescence bracts
    NA
    Inflorescence branching
    the inflorescence is on one or more stems with no branches
    Inflorescence crowding
    • NA
    • 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 roughly circular (not flattened) in cross-section
    Inflorescence type
    there is one spike or raceme at the tip of the stem
    Perianth composition
    • there are bristles attached at the base of the achene
    • there is no perianth on the plant
    Stamen number
    3
    Stigma number
    3
    Style division
    the top two thirds of the style is divided
    floral bristle barbs
    the bristles have tiny barbs on them
    plantlets budding at flower bases
    • no
    • yes

  • Fruits or seeds

    Achene beak length
    0 mm
    Achene surface texture
    the achene has tiny wrinkles that run cross-wise across the achene
    Achene tubercle relative width
    the tubercle is one half to two thirds as wide as the achene
    Achene tubercle width
    0.25–0.4 mm
    Capsule relative length
    NA
    Fruit cross-section
    the fruit is triangular to terete (circular) in cross-section
    Fruit length
    0.6–0.9 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) with a tubercle (a swelling or projection, usually of a different color or texture) on it
    Locules in capsule
    NA
    Seed length
    0 mm
    Seed tail relative length
    0 mm
    Seed tails
    NA
    Tubercle height
    0.05–0.3 mm

  • Growth form

    Lifespan
    the plant lives more than two years
    Rhizome thickness
    0.4–2 mm
    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
    NA
    Leaf blade length
    0 mm
    Leaf blade width
    0 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
    NA
    Leaf sheath hairs
    the leaf sheathes are without hairs
    Pedicel length (Typha)
    0 mm
    Stem leaf blade ligules
    NA
    Stem leaf blades
    there are no leaves on the main stem, or there is a small tooth or tiny blade, or a leaf sheath with no blade
    Width of seed-producing inflorescence
    1.5–2 mm

  • Place

    Habitat
    wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • man-made or disturbed habitats
    • meadows or fields
    • shores of rivers or lakes

  • Stem, shoot, branch

    Plant height
    5–90 cm
    Stem shape in cross-section
    • the stem is roughly quadrangular in cross-section
    • the stem is round or oval in cross-section
    Stem texture near tip
    the stem feels smooth near the tip
    Stem thickness at midpoint
    0.2–0.8 mm

Wetland status

Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)

In New England

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
unranked (S-rank: SNR)

var. pseudoptera

Vermont
extremely rare (S-rank: S1)

var. tenuis

Massachusetts
unranked (S-rank: SNR)

From Flora Novae Angliae dichotomous key

24.  Eleocharis tenuis (Willd.) J.A. Schultes N

slender spikesedge.  24a. Eleocharis capitata (L.) Br. var.  pseudoptera Weatherby ex Svens.; E. elliptica Kunth var.  pseudoptera (Weatherby ex Svens.) L. Harms;  24b. Eleocharis capitata, sensu Blake • CT, MA, ME, NH, RI, VT. Lake shores, stream shores, ditches, meadows, wet fields.

1a.  Achenes yellow, with 10–14 horizontal ridges through the length; stems sharply 4-angled, usually deeply sulcate, up to 0.8 mm wide; some or all of the upper leaf sheaths with a stout apical tooth 0.4–0.6 (–0.9) mm tall; tubercles very depressed 
 … 24a. E. tenuis var. pseudoptera (Weatherby ex Svens.) Svens.

1b.  Achenes green to brown-green, with 6–12 horizontal ridges through the length; stems bluntly and shallowly angled, up to 0.5 mm wide; upper leaf sheaths with a slender apical tooth to 0.2 mm tall; tuberlces often as tall as wide (rarely very depressed) 
 … 24b. E. tenuis var. tenuis

Variety tenuis is known from CT, MA, ME, NH, RI, VT. Variety pseudoptera is known from CT, MA, ME, VT. It is less common than var. tenuis and transitional, in some respects, to Eleocharis elliptica.

Native to North America?

Yes

Sometimes confused with

Eleocharis elliptica:
stems with 6-8 angles and fruits yellow to orange-yellow (vs. . tenuis, with stems with 4 or 5 angles and fruits usually green to brown green).

Synonyms

  • Eleocharis capitata, in the sense of Blake

Family

Cyperaceae

Genus

Eleocharis