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• Eleocharis equisetoides

Eleocharis equisetoides — horsetail spikesedge

Facts

Horsetail spikesedge is very rare in New England, with a few populations known from lake shores in Connecticut, Massachusetts and Rhode Island; indeed, it is listed as rare in many states where it occurs. The plant actually resembles a horsetail, with a rounded stem that is divided into sections by septa and is topped by a long, cylindrical spike reminiscent of the cone of a horsetail.

Habitat

Lacustrine (in lakes or ponds), shores of rivers or lakes

Characteristics

• Flowers

  Anther length

  2.6–3.2 mm

  Floral bristle color

  the bristles are slightly or strongly colored with reddish brown

  Floral bristle number

  • 1-4
  • 5-7
  • 8 or more

  Floral bristle relative length

  the bristles are between one tenth as long as the achene, and equal in length to 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

  4.8–7 mm

  Floral scale nerves

  7 or more

  Floral scale shape

  • the floral scales are oblong (rectangular but with rounded ends)
  • the floral scales are obovate (roughly egg-shaped, but with the widest part above the middle)

  Floral scale translucent

  the floral scales are opaque

  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

  • 1
  • 2
  • 3

  Stigma number

  • 2
  • 3

  Style division

  the top two thirds of the style is divided

  plantlets budding at flower bases

  no

• Fruits or seeds

  Achene beak length

  0 mm

  Achene surface texture

  the achene has stripes or ridges that run from end to end

  Achene tubercle relative width

  the tubercle is one half or less as wide as the achene

  Achene tubercle width

  0.5–0.7 mm

  Capsule relative length

  NA

  Fruit cross-section

  • the fruit is biconvex or elliptic (widest in the middle and tapering to both ends) in cross-section
  • the fruit is lenticular (lens-shaped) in cross-section
  • the fruit is triangular to terete (circular) in cross-section

  Fruit length

  1.8–2.3 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

  0.6–1.1 mm

• Growth form

  Lifespan

  the plant lives more than two years

  Rhizome thickness

  2–4 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

  4–8 mm

• Place

  Habitat

  • aquatic
  • wetlands

  New England state

  • Connecticut
  • Massachusetts
  • Rhode Island

  Specific habitat

  • in lakes or ponds
  • shores of rivers or lakes

• Stem, shoot, branch

  Plant height

  15–60 cm

  Stem shape 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

  5–8.4 mm

Wetland status

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

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae