Eleocharis equisetoides — horsetail spikesedge
![Stems and sheaths: Eleocharis equisetoides. ~ By Arthur Haines. ~ Copyright © 2025 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/eleocharis-equisetoides-ss-ahaines-d.jpg)
![Flowers and fruits: Eleocharis equisetoides. ~ By Arthur Haines. ~ Copyright © 2025 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/eleocharis-equisetoides-ff-ahaines-a.jpg)
![Inflorescences: Eleocharis equisetoides. ~ By Arthur Haines. ~ Copyright © 2025 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/eleocharis-equisetoides-in-ahaines-c.jpg)
![Plant form: Eleocharis equisetoides. ~ By Arthur Haines. ~ Copyright © 2025 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/eleocharis-equisetoides-ha-ahaines-b.jpg)
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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
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
-
- aquatic
- wetlands
- New England state
-
- Connecticut
- Massachusetts
- Rhode Island
- 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
- 1.8–2.3 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
- the fruit is triangular to terete (circular) in cross-section
-
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)
In New England
Distribution
- Connecticut
- present
- Maine
- absent
- Massachusetts
- present
- New Hampshire
- absent
- Rhode Island
- present
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Connecticut
- extremely rare (S-rank: S1), endangered (code: E)
- Massachusetts
- historical (S-rank: SH), #NAME? (code: #NAME?)
- Rhode Island
- rare (S-rank: S2), concern (code: C)
From Flora Novae Angliae dichotomous key
8. Eleocharis equisetoides (Ell.) Torr. NC
horsetail spikesedge. Scirpus equisetoides Ell. • CT, MA, RI. Lake shores, often growing in standing water.