Your help is appreciated. We depend on donations to help keep this site free and up to date for you. Can you please help us?

Donate

Native Plant Trust: Go Botany Discover thousands of New England plants

Eleocharis engelmannii — Engelmann's spikesedge

Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.

New England distribution

Adapted from BONAP data

Found this plant? Take a photo and post a sighting.

North America distribution

Adapted from BONAP data

enlarge

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)

Characteristics

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
Show all characteristics

  • 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)

New England distribution and conservation status

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)

var. detonsa

Massachusetts
extremely rare (S-rank: S1)

var. engelmannii

Massachusetts
extremely rare to rare (S-rank: S1S2)

Native to North America?

Yes

Sometimes confused with

Eleocharis obtusa:
tubercles 0.2-0.4 mm tall, styles usually trifid, and perianth bristles usually exceeding the tubercle (vs. E. engelmannii, with tubercles 0.12-0.23 mm tall, styles usually bifid, and perianth bristles usually not exceeding the tubercle).

Family

Cyperaceae

Genus

Eleocharis

Notes on subspecies and varieties in New England

Variety engelmannii is known from CT, MA, ME, RI. Variety detonsa is known from MA, ME.

Help

From the dichotomous key of Flora Novae Angliae

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.