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- Amerorchis rotundifolia
Amerorchis rotundifolia — round-leaved orchid
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Facts
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
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
Found this plant? Take a photo and post a sighting.
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
-
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
In New England
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)
From Flora Novae Angliae dichotomous key
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.
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