Eleocharis diandra — Wright's spikesedge
![Flowers and fruits: Eleocharis diandra. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/eleocharis-diandra-ff-ahaines-a.jpg)
![Plant form: Eleocharis diandra. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/eleocharis-diandra-ha-ahaines-b.jpg)
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Facts
Wright's spikesedge is a rare plant that occurs on sandy shores of only three rivers in New England (the Androscoggin, Connecticut and Merrimack Rivers), plus Lake Champlain. It is one of the smaller, spreading spikesedges in our area, with thin, soft, reclining stems topped by plump spikelets with orange-brown flower scales and achenes with flattened tubercles. It is threatened by ATV traffic and other trampling in its muddy shoreline habitats.
Habitat
Floodplain (river or stream floodplains), shores of rivers or lakes
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
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enlargeCharacteristics
- Habitat
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Vermont
- Stem shape 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
- 0.7–1 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 biconvex or elliptic (widest in the middle and tapering to both ends) in cross-section
- the fruit is lenticular (lens-shaped) in cross-section
-
Flowers
- Anther color (dry)
- the anthers range in color from white to tan or yellow to yellow-brown
- Anther length
- 0.2–0.3 mm
- Floral bristle color
- the bristles are pale brown to brown
- Floral bristle number
-
- 0
- 1-4
- Floral bristle relative length
-
- NA
- 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
- 1–1.5 mm
- Floral scale nerves
- 1
- Floral scale shape
- the floral scales are ovate (roughly egg-shaped)
- Floral scale translucent
- the floral scales are opaque
- 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
- 2
- Stigma number
- 2
- Style division
- the top two thirds of the style is divided
- floral bristle barbs
- the bristles do not have barbs on them
- plantlets budding at flower bases
-
- no
- yes
-
Fruits or seeds
- Achene beak length
- 0 mm
- Achene surface texture
- the achene is smooth (it has no detectable texture)
- Achene tubercle relative width
- the tubercle is one half to two thirds as wide as the achene
- Achene tubercle width
- 0.24–0.45 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
- Fruit length
- 0.7–1 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
- 0.1–0.2 mm
-
Growth form
- Lifespan
- the plant lives only a single year or less
- Rhizome thickness
- 0 mm
- 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
- 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
- 1–4 mm
-
Place
- Habitat
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Vermont
- Specific habitat
-
- river or stream floodplains
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 2–25 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
- 0.3–1 mm
Wetland status
Occurs only in wetlands. (Wetland indicator code: OBL)
In New England
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- absent
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- extremely rare (S-rank: S1), endangered (code: E)
- New Hampshire
- historical (S-rank: SH), endangered (code: E)
- Vermont
- extremely rare (S-rank: S1)
From Flora Novae Angliae dichotomous key
5. Eleocharis diandra C. Wright NC
Wright’s spikesedge. Eleocharis diandra C. Wright var. depressa Fern. • CT, MA, ME, NH, VT. Wet sand of major rivers and, rarely, lake shores. In New England known only from the Androscoggin, Connecticut, and Merrimack Rivers and Lake Champlain. This species has been frequently reported from fresh-tidal river shores (e.g., Seymour 1982, Gleason and Cronquist 1991). However, those reports are based on Eleocharis aestuum. Eleocharis diandra occurs in non-tidal situations, with the exception of its downstream populations on the Connecticut River in Hartford County, CT, where the river is minimally tidal.
Native to North America?
Yes