Schoenoplectus subterminalis (Torr.) Soják

water bulrush

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

Water bulrush has disjunct eastern and western populations in North America. It often forms lawnlike mats underwater in lakes and slow-moving rivers.

Habitat

Lacustrine (in lakes or ponds), riverine (in rivers or streams)

Characteristics

Habitat
aquatic
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Stem shape in cross-section
the stem is round or oval in cross-section
Leaf blade width
0.2–1 mm
Leaf blade cross-section
  • the leaf blade is elliptic or circular in cross-section
  • the leaf blade is flat or rolled in at the edges
Inflorescence position
the inflorescence appears to come from the side of the plant because the involucral bract at its base looks like an extension of the main stem
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
2.5–3.5 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 triangular to terete (circular) in cross-section
Show All Characteristics
  • Flowers
    Anther length
    2–3.5 mm
    Floral bristle color
    the bristles are pale brown to brown
    Floral bristle number
    5-7
    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
    4–6 mm
    Floral scale shape
    • the floral scales are lanceolate (widest below the middle, and tapering at both ends)
    • the floral scales are ovate (roughly egg-shaped)
    Floral scale translucent
    the floral scales are translucent
    Flower number per cluster
    1
    Inflorescence bract angle
    the bracts are vertical or angled only slightly outwards
    Inflorescence bract number
    there is just one bract on the inflorescence
    Inflorescence bract position (Sparganium)
    NA
    Inflorescence bracts
    there is only one bract, and it looks like a continuation of the stem
    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 appears to come from the side of the plant because the involucral bract at its base looks like an extension of the main stem
    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
    0.3–0.8 mm
    Achene surface texture
    the achene is smooth (it has no detectable texture)
    Achene tubercle relative width
    NA
    Achene tubercle width
    0 mm
    Capsule relative length
    NA
    Fruit cross-section
    the fruit is triangular to terete (circular) in cross-section
    Fruit length
    2.5–3.5 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) without a tubercle (a swelling or projection, usually of a different color or texture)
    Locules in capsule
    NA
    Seed length
    0 mm
    Seed tail relative length
    0 mm
    Seed tails
    NA
    Tubercle height
    0 mm
  • Growth form
    Lifespan
    the plant lives more than two years
    Rhizome thickness
    1 mm
    Underground organs
    • the plant has a rhizome (a horizontal underground stem with roots growing from it)
    • the plant has one or more swollen storage organs underground, such as bulbs or tubers
  • Leaves
    Auricle length
    0 mm
    Auricle texture
    NA
    Auricles
    there are no auricles on the leaf sheath
    Leaf blade cross-section
    • the leaf blade is elliptic or circular in cross-section
    • the leaf blade is flat or rolled in at the edges
    Leaf blade length
    Up to 50 mm
    Leaf blade width
    0.2–1 mm
    Leaf form
    the leaves are extremely fine, or they are floating leaves, and do not 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
    the leaf blades do not have transverse septa
    Leaf sheath hairs
    the leaf sheathes are without hairs
    Pedicel length (Typha)
    0 mm
    Stem leaf blade ligules
    the plant has ligules at the leaf blade bases
    Stem leaf blades
    • there are fully-developed leaves with leaf blades on the main stem
    • 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
    4–7 mm
  • Place
    Habitat
    aquatic
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • in lakes or ponds
    • in rivers or streams
  • Stem, shoot, branch
    Plant height
    20–150 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
    0.5–1 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
present
Vermont
present

Conservation Status

Exact status definitions can vary from state to state. For details, please check with your state.

Rhode Island
extremely rare (S-rank: S1), state threatened (code: ST)
Vermont
uncommon (S-rank: S3)

Native to North America?

Yes

Synonyms

  • Scirpus subterminalis Torr.

Family

Cyperaceae

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Information from Dichotomous Key of Flora Novae Angliae

9.  Schoenoplectus subterminalis (Torr.) Soják N

water bulrush. Scirpus subterminalis Torr. • CT, MA, ME, NH, RI, VT. Shallow water of lakes and slow-moving rivers, often forming large mats of thin, flaccid, narrow leaves underwater.