Amerorchis rotundifolia (Banks ex Pursh) Hultén

round-leaved orchid

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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

Round-leaved orchid is a rare inhabitant of high-pH swamps and fens, usually under northern white-cedar (Thuja occidentalis). It is also found on Canadian and Alaskan tundra. Within New England it is known from northern Maine, and has been collected in the past in New Hampshire and Vermont.

Habitat

Fens, swamps

Characteristics

Habitat
wetlands
New England state
  • Maine
  • New Hampshire
  • Vermont
Leaf arrangement
basal: the leaves are growing only at the base of the plant
Number of leaves on stem
absent
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
  • pink to red
  • white
Nectar spur
the flower has at least one nectar spur on it
Inflorescence type
  • the inflorescence is a raceme (a long unbranched stem with stalked flowers growing along it)
  • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
Lower petal characteristics
  • the labellum has spurs on it
  • the labellum is lobed
Lower petal length
6–10 mm
Sepal length
6–10 mm
Show All Characteristics
  • Flowers
    Flower bract length
    5–15 mm
    Flower petal color
    • pink
    • purple
    • red
    • white
    Flower symmetry
    there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
    Flowering date
    • July
    • June
    Flowers per inflorescence
    1–17
    Form of lower petal
    the labellum does not have a pouch-like shape
    Hairs on inflorescence axis
    the main stem of the inflorescence is hairless
    Inflorescence length
    40–80 mm
    Inflorescence type
    • the inflorescence is a raceme (a long unbranched stem with stalked flowers growing along it)
    • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
    Labellum position
    the labellum is in the lower position on the flower
    Length of flower stalk
    At least 0 mm
    Length of narrowed base of lower petal
    0 mm
    Length of peduncle
    100–250 mm
    Lobes at base of lower petal
    0 mm
    Lower petal characteristics
    • the labellum has spurs on it
    • the labellum is lobed
    Lower petal length
    6–10 mm
    Lower petal outline
    the labellum is lobed but not fringed
    Lower petal strongly red-veined
    no
    Main color of lower petal
    • pink to red
    • white
    Nectar spur
    the flower has at least one nectar spur on it
    Number of stamens
    1
    Orientation of side petals
    the lateral petals are angled steeply upwards
    Self-pollinating flowers
    there are no cleistogamous flowers on this plant
    Sepal length
    6–10 mm
    Sepals fused only to sepals
    the sepals are separate from one another
    Spots on lower petal
    yes
    Spur opening membrane
    there is no membrane over the spur opening
  • 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
    • there are only slender roots on the plant
    • this plant has a rhizome (a horizontal underground stem with roots growing from it)
  • 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
    basal: the leaves are growing only at the base of the plant
    Leaf blade edges
    the edges of the leaf blade have no teeth
    Leaf blade length
    27–110 mm
    Leaf blade length to width ratio
    1.4–2.3
    Leaf blade shape
    • the leaf blade is elliptic (widest near the middle and tapering at both ends)
    • the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    • the leaf blade is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
    • the leaf blade is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    • the leaf blade is orbicular (roughly circular, as wide as long)
    • 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 acuminate (tapers to a long, thin point)
    • the tip of the leaf blade is acute (sharply pointed)
    • the tip of the leaf blade is obtuse (bluntly pointed)
    Leaf blade width
    12–80 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
    absent
  • Place
    Habitat
    wetlands
    New England state
    • Maine
    • New Hampshire
    • Vermont
    Specific habitat
    • fens
    • swamps

Wetland Status

Not classified

New England Distribution and Conservation Status

Distribution

Connecticut
absent
Maine
present
Massachusetts
absent
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
rare (S-rank: S2), threatened (code: T)
New Hampshire
historical (S-rank: SH), endangered (code: E)
Vermont
historical (S-rank: SH)

Native to North America?

Yes

Sometimes Confused With

Corallorhiza maculata:
flowers with a nectary spur and plants reddish, with only bract-like leaves on the stem (vs. A. rotundifolia, with flowers with a nectary spur and plants green, with a broad, expanded green basal leaf).

Synonyms

  • Galearis rotundifolia (Banks ex Pursh) R.M. Bateman
  • Habenaria rotundifolia (Banks ex Pursh) Richards.
  • Orchis rotundifolia Banks ex Pursh

Family

Orchidaceae

Genus

Amerorchis

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Information from Dichotomous Key of Flora Novae Angliae

1.  Amerorchis rotundifolia (Banks ex Pursh) Hultén NC

round-leaved orchid. Galearis rotundifolia (Banks ex Pursh) R.M. Bateman; Habenaria rotundifolia (Banks ex Pursh) Richards.; Orchis rotundifolia Banks ex Pursh • ME, NH, VT. 
High-pH swamps and fens, usually in the shade of Thuja occidentalis.