Eleocharis engelmannii — Engelmann's spikesedge
![Flowers and fruits: Eleocharis engelmannii. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/eleocharis-engelmannii-detonsa-ff-ahaines.jpg)
Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.
Facts
Engelmann's spikesedge is found on pond shores, temporary pools and wet, sandy/muddy/peaty areas in Connecticut, Massachusetts, Maine and Rhode Island. There are two varieties in New England. Eleocharis engelmannii var. engelmannii occurs in Connecticut, Massachusetts, Maine and Rhode Island, whereas E. engelmannii var. detonsa is known only from Massachusetts and Maine (where it may have been extirpated). Engelmann’s spikerush can be distinguished from other species by its bent tubercle that is not constricted at the base, fibrous roots, a narrow-cylindric spike, and very short perianth bristles.
Habitat
Anthropogenic (man-made or disturbed habitats), shores of rivers or lakes, wetland margins (edges of wetlands)
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.
Found this plant? Take a photo and post a sighting.
enlargeCharacteristics
- Habitat
- wetlands
- New England state
-
- Connecticut
- Maine
- 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
- 0.9–1.5 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
-
Flowers
- Anther color (dry)
- the anthers range in color from white to tan or yellow to yellow-brown
- Anther length
- 0.3–1 mm
- Floral bristle color
- the bristles are pale brown to brown
- Floral bristle number
-
- 0
- 1-4
- 5-7
- Floral bristle relative length
-
- the bristles are longer than 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
- 2–2.5 mm
- Floral scale nerves
- 1
- Floral scale shape
- the floral scales are ovate (roughly egg-shaped)
- Floral scale translucent
- the floral scales are opaque
- 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
- 3
- Stigma number
-
- 2
- 3
- Style division
- the top two thirds of the style is divided
- 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 two thirds to about as wide as the achene
- Achene tubercle width
- 0.46–0.9 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
- Fruit length
- 0.9–1.5 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
- 0.12–0.23 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
- 2–4 mm
-
Place
- Habitat
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- Rhode Island
- Specific habitat
-
- edges of wetlands
- man-made or disturbed habitats
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 2–40 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
- 0.5–2 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
- absent
- Rhode Island
- present
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Maine
- historical (S-rank: SH), potentially extirpated (code: PE)
- Massachusetts
- unranked (S-rank: SNR)
var. detonsa
- Massachusetts
- extremely rare to rare (S-rank: S1S2), #NAME? (code: #NAME?)
var. engelmannii
- Massachusetts
- extremely rare to rare (S-rank: S1S2), #NAME? (code: #NAME?)
From Flora Novae Angliae dichotomous key
7. Eleocharis engelmannii Steud. N
Engelmann’s spikesedge. 7a. Eleocharis monticola Fern. var. leviseta Fern.; E. obtusa (Willd.) J.A. Schultes var. detonsa (Gray) Drapalick & Mohlenbrock; 7b. Eleocharis monticola Fern.; E. obtusa (Willd.) J.A. Schultes var. engelmannii (Steud.) Britt. • CT, MA, ME, RI; also reported from NH by Smith et al. (2002), but specimens are unknown. Pond shores, temporary pools, and open, disturbed, hydric soils.
1a. Perianth bristles lacking or, if present, numbering 2–4, smooth, and shorter than the length of the achene body … 7a. E. engelmannii var. detonsa Gray in H. Patters.
1b. Perianth bristles numbering 5–7 per achene, retrorse-barbellate, exceeding the length of the achene body … 7b. E. engelmannii var. engelmannii
Variety engelmannii is known from CT, MA, ME, RI. Variety detonsa is known from MA, ME.
Native to North America?
Yes