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Malaxis monophyllos — white adder's-mouth

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Facts

White adder's-mouth has a circumboreal distribution, but is rare in New England. It is usually found in fens and swamps with northern white-cedar (Thuja occidentalis).

Habitat

Fens (calcium-rich wetlands), ridges or ledges, swamps

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont
Leaf arrangement
alternate: there is one leaf per node along the stem
Number of leaves on stem
  • one
  • two
Form of lower petal
the labellum does not have a pouch-like shape
Lower petal outline
the labellum is lobed but not fringed
Main color of lower petal
  • green to brown
  • white
  • yellow
Nectar spur
there are no nectar spurs on the flower
Inflorescence type
the inflorescence is a raceme (a long unbranched stem with stalked flowers growing along it)
Lower petal characteristics
the labellum is lobed
Lower petal length
1.3–2.2 mm
Sepal length
1.5–2.5 mm
Show all characteristics

  • Flowers

    Flower bract length
    1.5–2 mm
    Flower petal color
    • green
    • white
    • yellow
    Flower symmetry
    there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
    Flowering date
    • August
    • July
    • June
    Flowers per inflorescence
    5–80
    Form of lower petal
    the labellum does not have a pouch-like shape
    Hairs on flower stalk
    the flower stalk has no hairs on it
    Hairs on inflorescence axis
    the main stem of the inflorescence is hairless
    Inflorescence length
    10–120 mm
    Inflorescence type
    the inflorescence is a raceme (a long unbranched stem with stalked flowers growing along it)
    Labellum position
    the labellum is in the lower position on the flower
    Length of flower stalk
    2–4.5 mm
    Length of narrowed base of lower petal
    0 mm
    Length of peduncle
    100–250 mm
    Lower petal characteristics
    the labellum is lobed
    Lower petal length
    1.3–2.2 mm
    Lower petal outline
    the labellum is lobed but not fringed
    Lower petal strongly red-veined
    no
    Main color of lower petal
    • green to brown
    • white
    • yellow
    Nectar spur
    there are no nectar spurs on the flower
    Nectar spur length
    0 mm
    Number of stamens
    1
    Orientation of side petals
    • the lateral petals are angled steeply upwards
    • the lateral petals slant outward
    Self-pollinating flowers
    there are no cleistogamous flowers on this plant
    Sepal length
    1.5–2.5 mm
    Sepals fused only to sepals
    the sepals are separate from one another
    Spots on lower petal
    no
    Spur opening membrane
    NA
    Spur opening shape
    NA

  • Fruits or seeds

    Seed capsule orientation
    the capsule points upwards or is angled outwards

  • Growth form

    Plant green or not
    the plant is chlorophyllous (it has green parts)
    Roots
    the rhizomes do not resemble coral
    Underground organs
    • the plant has one or more swollen storage organs underground, such as bulbs, tubers or corms
    • there are only slender roots on the plant

  • Leaves

    Bract relative length
    the bract is shorter than the associated flower
    Features of leaves
    the leaf does not have any of the mentioned special features
    Leaf arrangement
    alternate: there is one leaf per node along the stem
    Leaf blade edges
    the edges of the leaf blade have no teeth
    Leaf blade length
    15–95 mm
    Leaf blade length to width ratio
    1.5–1.9
    Leaf blade shape
    • the leaf blade is elliptic (widest near the middle and tapering at both ends)
    • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    Leaf blade tip
    the tip of the leaf blade is acute (sharply pointed)
    Leaf blade width
    10–50 mm
    Leaves during flowering
    there are leaves on the plant when it is flowering
    Number of bracts on stem
    0
    Number of leaves on stem
    • one
    • two

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Vermont
    Specific habitat
    • fens (calcium-rich wetlands)
    • ridges or ledges
    • swamps

Wetland status

Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)

In New England

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.

Maine
extremely rare (S-rank: S1), endangered (code: E)

ssp. brachypoda

New Hampshire
historical (S-rank: SH), endangered (code: E)

var. brachypoda

Massachusetts
extremely rare (S-rank: S1), endangered (code: E)
Vermont
rare to uncommon (S-rank: S2S3), threatened (code: T)

From Flora Novae Angliae dichotomous key

2.  Malaxis monophyllos (L.) Sw. ssp. brachypoda (Gray) A. & D. Löve NC

white adder’s-mouth. Malaxis brachypoda (Gray) Fern.; M. monophyllos (L.) Sw. var. brachypoda (Gray) F. Morris & Eames • CT, MA, ME, NH, VT; widespread (at least historically) in the northern states, but missing from southern and eastern-central New England. Fens and evergreen swamps, usually in the shade of Thuja occidentalis, rarely on open ledges.

Native to North America?

Yes

Sometimes confused with

Malaxis unifolia

Family

Orchidaceae

Genus

Malaxis