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Schoenoplectus heterochaetus — slender bulrush

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Facts

Slender bulrush is found along lake and river shores in shallow water or wet soils. It is rare in New England, with populations in Massachusetts and Vermont.

Habitat

Shores of rivers or lakes

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • aquatic
  • wetlands
New England state
  • Massachusetts
  • Vermont
Stem shape in cross-section
the stem is round or oval in cross-section
Leaf blade width
Up to 5 mm
Leaf blade 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
  • the inflorescence is at the tip of the plant
Inflorescence branching
the inflorescence is branched
Fruit type (general)
the fruit is like a seed, and surrounded by scales
Fruit length
2.2–3.2 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
    1.5–3.5 mm
    Floral bristle color
    the bristles are pale brown to brown
    Floral bristle number
    • 1-4
    • 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
    the floral scales have hairs on them
    Floral scale length
    3–4 mm
    Floral scale shape
    • the floral scales are oblong (rectangular but with rounded ends)
    • the floral scales are ovate (roughly egg-shaped)
    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 branched
    Inflorescence crowding
    the inflorescence is at least somewhat spread out, with at least one branch coming from the main stem
    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
    • 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 are two or more flowers, spikes or flower clusters on a branched inflorescence
    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
    0.3–1 mm
    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
    2.2–3.2 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
    5–8 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
    the leaf blade is flat or rolled in at the edges
    Leaf blade length
    Up to 220 mm
    Leaf blade width
    Up to 5 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
    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

  • Place

    Habitat
    • aquatic
    • wetlands
    New England state
    • Massachusetts
    • Vermont
    Specific habitat
    shores of rivers or lakes

  • Stem, shoot, branch

    Plant height
    150–250 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
    1–10 mm

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

In New England

Distribution

Connecticut
absent
Maine
absent
Massachusetts
present
New Hampshire
absent
Rhode Island
absent
Vermont
present

Conservation status

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

Massachusetts
historical (S-rank: SH), #NAME? (code: #NAME?)
Vermont
rare (S-rank: S2)

From Flora Novae Angliae dichotomous key

5.  Schoenoplectus heterochaetus (Chase) Soják NC

slender bulrush. Scirpus heterochaetus Chase; S. lacustris L. var. tenuiculmis Sheldon • MA, VT. Shallow water or wet soil of lake and river shores. It is useful to know (for hybrid detection) that Schoenoplectus heterochaetus has 6–9 aerenchymal lacunae in cross-section at ⅔ stem height that are mostly 0.4–0.9 mm in diameter. These characteristics are inherited additively (i.e., are intermediate) in hybrid plants. See the identification key for the character states of 
 S. acutus and S. tabernaemontani.

1×5. Schoenoplectus acutus × Schoenoplectus heterochaetus → Schoenoplectus ×‌oblongus (T. Koyama) Soják is a rare hybrid in New England known from MA, RI, VT. It typically shows a high proportion of solitary spikelets (30–80% of the spikelets are solitary vs. 0–20% in S. acutus). However, the achenes are weakly trigonous in cross-section and commonly have 4 or 5 perianth bristles. Also, each spikelet usually shows a mixture of bifid and trifid styles.

5×10. Schoenoplectus heterochaetus × Schoenoplectus tabernaemontani → Schoenoplectus ×‌steinmetzii (Fern.) S.G. Sm. is a very rare bulrush 
hybrid in New England. It shows a high proportion of solitary spikelets (similar to 
 S. heterochaetus); however, the achenes are weakly trigonous in cross-section and 
have usually 4 or 5 perianth bristles. Also, the stems have 5–7 aerenchymal lacunae 
in cross-section at ⅔ stem height that are mostly 0.7–1.4 mm in diameter. This 
hybrid is known only from ME within New England (it is still extant at the type locality).

Native to North America?

Yes

Sometimes confused with

Schoenoplectus acutus
Schoenoplectus tabernaemontani

Family

Cyperaceae

Genus

Schoenoplectus