Equisetum palustre L.

marsh horsetail

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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

Marsh horsetail is found on lake and stream shores, marshes, seeps and pools. It contains two chemicals that have been shown to be poisonous to horses: thiaminase, which breaks down vitamin B1, and palustrine, an alkaloid. It is important, therefore, for anyone raising horses to know if this species is growing in the pasture or in an area from which hay is going to be cut.

Habitat

Marshes, shores of rivers or lakes, wetland margins (edges of wetlands)

Characteristics

Habitat
wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont
Stem form
the stem is relatively straight
Branches
  • there are branches off the main stem, but these branches are not branched
  • there are no branches off the main stem
Cone tip shape
The tip of the spore cone is blunt
Sheathes on older stems
the leaf sheathes persist in older stems
Sheath color
the leaf sheath is mainly black
Stem cross-section
up to half of the stem diameter is occupied by the hollow central cavity
Number of stem ridges
5–10
Stem color
the aerial stem color is green
Sheath border color
the border of the leaf sheath has a wide white edge
Length of branch section
the first internode of the branch is shorther than the associated stem sheath
Show All Characteristics
  • Leaves
    Leaf length
    2–5 mm
    Leaves per node
    5–10
    Sheath border color
    the border of the leaf sheath has a wide white edge
    Sheath color
    the leaf sheath is mainly black
    Sheathes on older stems
    the leaf sheathes persist in older stems
  • Place
    Habitat
    wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Vermont
    Specific habitat
    • edges of wetlands
    • marshes
    • shores of rivers or lakes
  • Spores or spore cones
    Cone length
    9–35 mm
    Cone tip shape
    The tip of the spore cone is blunt
    Spore form
    the spores are green and spherical
  • Stem, shoot, branch
    Branch grooves
    the interior of the groove is U-shaped
    Branches
    • there are branches off the main stem, but these branches are not branched
    • there are no branches off the main stem
    How hollow is stem
    17–33
    Length of branch section
    the first internode of the branch is shorther than the associated stem sheath
    Number of stem ridges
    5–10
    Plant height
    200–800 mm
    Stem cavities
    8
    Stem color
    the aerial stem color is green
    Stem cross-section
    up to half of the stem diameter is occupied by the hollow central cavity
    Stem differences
    the vegetative and reproductive stems are similar in appearance
    Stem form
    the stem is relatively straight
    Stem thickness
    1–5 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
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
historical (S-rank: SH), special concern, extirpated (code: SC*)
Massachusetts
historical (S-rank: SH), #NAME? (code: #NAME?)
New Hampshire
extremely rare (S-rank: S1), endangered (code: E)
Vermont
rare (S-rank: S2), threatened (code: T)

Native to North America?

Yes

Sometimes Confused With

Equisetum fluviatile:
nodes with 12-24 leaves per sheath, each leaf with a very narrow white margin (vs. E. palustre, with nodes with 5-10 leaves per sheath, each leaf with a relatively broad white margin).

Synonyms

  • Equisetum palustre var. americanum Vict.

Family

Equisetaceae

Genus

Equisetum

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Information from Dichotomous Key of Flora Novae Angliae

4.  Equisetum palustre L. N

marsh horsetail. Equisetum palustre L. var. americanum Vict. • CT, MA, ME, NH, VT; scattered in southern New England. Lake and stream shores, marshes, river shore seeps, and pools.