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Neottia convallarioides — broad-leaved twayblade

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Facts

Broad-leaved twayblade has a disjunct distribution in North America, with populations in the Northeast and Great Lakes regions, as well as west of the Great Plains, from Arizona to the Aleutian Islands. A study in New Hampshire, where the species is threatened, showed that populations near hiking trails showed signs of trampling.

Habitat

Floodplain (river or stream floodplains), 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
  • Maine
  • New Hampshire
  • Vermont
Leaf arrangement
  • alternate: there is one leaf per node along the stem
  • opposite: there are two leaves per node along the stem
  • whorled: there are three or more leaves per node along the stem
Number of leaves on stem
  • three
  • 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
8–13 mm
Sepal length
4.5–5.5 mm
Show all characteristics

  • Flowers

    Flower bract length
    3–5 mm
    Flower petal color
    • green
    • 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
    5–20
    Form of lower petal
    the labellum does not have a pouch-like shape
    Hairs on flower stalk
    the flower stalk has at least some hairs with glands at their bases or tips
    Hairs on inflorescence axis
    at least some of the hairs on the main stem of the inflorescence have glands
    Inflorescence length
    20–120 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
    2.5–7 mm
    Lobes at base of lower petal
    0 mm
    Lower petal characteristics
    the labellum is lobed
    Lower petal length
    8–13 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 slant outward
    • the lateral petals slant somewhat downward
    Pollen sacs
    the pollinia remain intact and do not fragment into smaller parts
    Self-pollinating flowers
    there are no cleistogamous flowers on this plant
    Sepal length
    4.5–5.5 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
    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
    • opposite: there are two leaves per node along the stem
    • whorled: there are three or more leaves per node along the stem
    Leaf blade edges
    the edges of the leaf blade have no teeth
    Leaf blade length
    20–70 mm
    Leaf blade length to width ratio
    1.2–1.3
    Leaf blade shape
    • the leaf blade is elliptic (widest near the middle and tapering at both ends)
    • 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 acute (sharply pointed)
    • the tip of the leaf blade is obtuse (bluntly pointed)
    Leaf blade width
    15–58 mm
    Leaves during flowering
    there are leaves on the plant when it is flowering
    Number of bracts on stem
    2–3
    Number of leaves on stem
    • three
    • two

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Maine
    • New Hampshire
    • Vermont
    Specific habitat
    • river or stream floodplains
    • swamps

Wetland status

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

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.

New Hampshire
rare (S-rank: S2), threatened (code: T)
Vermont
uncommon (uncertain) (S-rank: S3?)

From Flora Novae Angliae dichotomous key

3.  Neottia convallarioides (Sw.) Rich. N

broad-leaved twayblade. Bifolium convallarioides (Sw.) Nieuwl.; Epipactis convallarioides Sw.; Listera convallarioides (Sw.) Nutt. ex Ell.; Ophrys convallarioides (Sw.) W. Wight ex House • ME, NH, VT. Swamps and streambanks, often in the shade of Thuja occidentalis.

1×3. Neottia auriculata × Neottia convallarioides → Neottia ×‌veltmanii (Case) Baumbach is a rare twayblade hybrid known from ME but is to be expected elsewhere in northern New England. It is usually associated with one or both parents (i.e., it is not typically found alone). It has the basally narrowed labellum of N. convallarioides and, like that species, has stipitate glands on the pedicels and ovary. However, the stipitate glands on these parts are shorter and sparser than those of the inflorescence axis (in N. convallarioides, the stipitate glands are similar in length and ± similar in density on the glandular portions of the inflorescence). Further, the hybrid shows a small pair of outward pointing auricles at the very base of the lip (rather than a small pair of teeth distal to the narrow portion of the labellum).

Native to North America?

Yes

Sometimes confused with

Neottia auriculata:
labellum maintaining its width and not narrowed at the base, bearing a pair of retrorse auricles at the base, and pedicels and ovary glabrous, only the axis of the inflorescence stipitate-glandular (vs. N. convallorioides, with the labellum narrowed at the base, usually bearing a pair of small teeth at the base, and axis of the inflorescence, pedicels, and ovary stipitate-glandular).

Synonyms

  • Bifolium convallarioides (Sw.) Nieuwl.
  • Epipactis convallarioides Sw.
  • Neottia convallarioides (Sw.) Rich.
  • Ophrys convallarioides (Sw.) W. Wight ex House

Family

Orchidaceae

Genus

Neottia