Eleocharis robbinsii — Robbins' spikesedge

Characteristics

• Flowers

  Anther length

  1.6–3.2 mm

  Floral bristle color

  the bristles are slightly or strongly colored with reddish brown

  Floral bristle number

  5-7

  Floral bristle relative length

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

  Floral bristles

  the bristles are strongly bent or curled

  Floral scale hairs

  there are no hairs on the floral scales

  Floral scale length

  5–7.8 mm

  Floral scale nerves

  7 or more

  Floral scale shape

  • the floral scales are lanceolate (widest below the middle, and tapering at both ends)
  • the floral scales are ovate (roughly egg-shaped)

  Floral scale translucent

  the floral scales are opaque

  Flower number per cluster

  • 2-5
  • 5-20

  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

  Stamen number

  • 1
  • 2
  • 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 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

  0.3–0.7 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 triangular to terete (circular) in cross-section

  Fruit length

  1.9–2.6 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) 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

  0.5–1.1 mm

• Growth form

  Lifespan

  the plant lives more than two years

  Rhizome thickness

  0.5–2 mm

  Underground organs

  • the plant has a rhizome (a horizontal underground stem with roots growing from it)
  • the plant has one or more swollen storage organs underground, such as bulbs or tubers

• 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
  • the leaves are extremely fine, or they are floating leaves, and do not 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

  1.5–3 mm

• Place

  Habitat

  • aquatic
  • wetlands

  New England state

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

  Specific habitat

  • in lakes or ponds
  • in rivers or streams
  • shores of rivers or lakes

• Stem, shoot, branch

  Plant height

  16–70 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

  Stem thickness at midpoint

  0.7–0.9 mm

Wetland status

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

In New England

From Flora Novae Angliae dichotomous key