Eleocharis intermedia — mudflat spikesedge
![Plant form: Eleocharis intermedia. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Cyperaceae/eleocharis-intermedia-ha-ahaines-b.jpg)
![Flowers and fruits: Eleocharis intermedia. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Cyperaceae/eleocharis-intermedia-ff-ahaines-a.jpg)
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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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enlargeFacts
Mudflat spikesedge inhabits sandy or muddy streamsides and pond edges, and river sand bars. It is often found in areas with high-pH bedrock. It is considered "threatened" in Massachusetts, where it reaches the northern edge of its range. It is a small, annual plant that forms mats of densely tufted plants with wiry stems. The yellow-brown achenes ripen in mid-to-late summer, and are topped by a "dunce-cap" -- a long, cylindrical tubercle.
Habitat
Anthropogenic (man-made or disturbed habitats), bogs, floodplain (river or stream floodplains), shores of rivers or lakes
Characteristics
- Habitat
-
- aquatic
- 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
- 1.2–1.5 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
- Fruit cross-section
-
- the fruit is lenticular (lens-shaped) in cross-section
- the fruit is triangular to terete (circular) in cross-section
-
Flowers
- Anther length
- 0.2–0.5 mm
- Floral bristle color
- the bristles are pale brown to brown
- Floral bristle number
- 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
- 1.7–2.5 mm
- Floral scale nerves
- 1
- Floral scale shape
- the floral scales are ovate (roughly egg-shaped)
- Floral scale translucent
- the floral scales are translucent
- 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
- 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
-
Fruits or seeds
- Achene beak length
- 0 mm
- Achene surface texture
- the achene has very tiny pits or depressions on it
- Achene tubercle relative width
- the tubercle is one half or less as wide as the achene
- Achene tubercle width
- 0.1–0.25 mm
- Capsule relative length
- NA
- Fruit cross-section
-
- the fruit is lenticular (lens-shaped) in cross-section
- the fruit is triangular to terete (circular) in cross-section
- Fruit length
- 1.2–1.5 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
- 0.3–0.4 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
- 0–1 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
- 1–2 mm
-
Place
- Habitat
-
- aquatic
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Vermont
- Specific habitat
-
- bogs
- man-made or disturbed habitats
- river or stream floodplains
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 4–40 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
- 0.2–0.5 mm
Wetland status
Occurs only in wetlands. (Wetland indicator code: OBL)
New England distribution and conservation status
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.
- Connecticut
- unrankable (S-rank: SU)
- Maine
- rare (S-rank: S2)
- Massachusetts
- rare (S-rank: S2), threatened (code: T)
- New Hampshire
- extremely rare (S-rank: S1), endangered (code: E)
- Vermont
- uncommon (S-rank: S3)
Native to North America?
Yes
Sometimes confused with
- Eleocharis flavescens:
- styles usually bifid, achenes biconvex, and leaf sheaths prolonged at summit into a white, scarious tip (vs. E. intermedia, with styles trifid, achenes compressed-trigonous, and leaf sheaths variable at apex, but without a prolonged white, scarious apex).
- Eleocharis microcarpa:
- achenes pale, nearly white, 0.5-1 mm long, and floral scales 1-1.5 mm long (vs. E. intermedia, with achenes green to brown-green, 1.2-1.5 mm long, and floral scales 1.7-2.5 mm long).
Family
Genus
From the dichotomous key of Flora Novae Angliae
12. Eleocharis intermedia J.A. Schultes N
mudflat spikesedge. CT, MA, ME, NH, VT. Sandy, muddy, or boggy margins of streams and ponds, often associated with areas of high-pH bedrock or till, also frequent in areas of disturbance (e.g., accretion bars along rivers).