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Spiranthes lacera — slender ladies'-tresses

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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

Slender ladies'-tresses is the easiest species of ladies'-tresses to identify, due to the distinctive green or yellowish-green spot on the center of the labellum (lower modified petal). It tolerates a range of dry to moist habitats including roadsides, and is pollinated by bumblebees. The Ojibwa used the roots of slender ladies'-tresses as an ingredient in a charm to bring luck to hunters. Note that there are two varieties in New England, as well as a couple of rare hybrids.

Habitat

Anthropogenic (man-made or disturbed habitats), grassland, meadows and fields, ridges or ledges, woodlands

Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf arrangement
basal: the leaves are growing only at the base of the plant
Number of leaves on stem
one
Form of lower petal
the labellum does not have a pouch-like shape
Lower petal outline
the labellum is simple in form
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)
  • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
Lower petal characteristics
the labellum is simple in form
Lower petal length
3–6.5 mm
Show all characteristics

  • Flowers

    Flower petal color
    white
    Flower symmetry
    there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
    Flowering date
    • August
    • July
    • September
    Flowers per inflorescence
    9–35
    Form of lower petal
    the labellum does not have a pouch-like shape
    Hairs on flower stalk
    NA
    Hairs on inflorescence axis
    • at least some of the hairs on the main stem of the inflorescence have glands
    • the main stem of the inflorescence is hairless
    Inflorescence length
    30–200 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
    0 mm
    Lobes at base of lower petal
    0 mm
    Lower petal characteristics
    the labellum is simple in form
    Lower petal length
    3–6.5 mm
    Lower petal outline
    the labellum is simple in form
    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 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
    Sepals fused only to sepals
    the sepals are separate from one another
    Shape of viscidium
    • the viscidium is lance-shaped (wider near one end, pointed at the ends)
    • the viscidium is long and narrow
    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
    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
    20–50 mm
    Leaf blade length to width ratio
    2–2.5
    Leaf blade shape
    the leaf blade is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    Leaf blade width
    10–20 mm
    Leaves during flowering
    • there are leaves on the plant when it is flowering
    • there are no leaves on the plant when it is flowering
    Number of bracts on stem
    At least 5
    Number of leaves on stem
    one

  • Place

    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • grasslands
    • man-made or disturbed habitats
    • meadows or fields
    • ridges or ledges
    • woodlands

Wetland status

Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)

New England distribution and conservation status

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Maine
fairly widespread (S-rank: S4)

var. gracilis

Maine
historical (S-rank: SH), potentially extirpated (code: PE)
Massachusetts
fairly widespread (S-rank: S4)
New Hampshire
uncommon (S-rank: S3), W (code: W)
Vermont
historical (S-rank: SH)

var. lacera

Massachusetts
fairly widespread (S-rank: S4)
Vermont
uncommon (S-rank: S3)

Native to North America?

Yes

Sometimes confused with

Spiranthes casei:
leaves narrow-lanceolate to oblanceolate, mostly 5–10 times as long as wide, basal and also on lower stem, and labellum cream-white to green-white, sometimes yellow near center (vs. S. lucida, with leaves narrow-ovate to obovate, 1–3.5 times as long as wide, strictly basal or sometimes withering prior to anthesis, and labellum with a central green or yellow-green spot).
Spiranthes lucida:
basal leaves elliptic-lanceolate, mostly 4-6 times as long as wide, and plants flowering June through July (vs. S. lacera, with basal leaves narrow-ovate to obovate, 1-3.5 times as long as wide, present after or anthesis or withering, and plants flowering July through mid-September).

Synonyms

  • Gyrostachys gracilis (Bigelow) Kuntze
  • Ibidium gracile (Bigelow) House
  • Neottia gracilis Bigelow
  • Spiranthes gracilis (Bigelow) Beck

Family

Orchidaceae

Genus

Spiranthes

Notes on subspecies and varieties in New England

Spiranthes lacera var. gracilis (Bigelow) Luer is known from CT, MA, ME, NH, RI, VT.S. lacera (Raf.) Raf. var. lacera is the more common form, known from CT, MA, ME, NH, RI, VT.

Help

From the dichotomous key of Flora Novae Angliae

3.  Spiranthes lacera (Raf.) Raf. N

slender ladies’-tresses.  3a. Gyrostachys gracilis (Bigelow) Kuntze; Ibidium gracile (Bigelow) House; Neottia gracilis Bigelow; Spiranthes gracilis (Bigelow) Beck;  3b. Neottia lacera Raf. 
• CT, MA, ME, NH, RI, VT. Xeric to mesic meadows, fields, woodlands, and roadsides.

1a.  Flowers relatively densely arranged on the spike, loosely to tightly spiraled, the ratio of spike length in mm to flower number less than 2.3; basal leaves usually absent at anthesis; rachis of inflorescence glabrous … 3a. S. lacera var. gracilis (Bigelow) Luer

1b.  Flowers relatively loosely arranged on the spike, secund to loosely spiraled, the ratio of spike length in mm to flower number equal to or greater than 2.3; basal leaves usually persisting through anthesis; rachis of inflorescence sparsely pubescent 
 … 3b. S. lacera var. lacera

Variety gracilis is known from CT, MA, ME, NH, RI, VT. Vareity lacera is known from CT, MA, 
ME, NH, RI, VT. Variety gracilis is more restricted and is limited in ME to the southern portion 
of the state.

3a×7.  Spiranthes ×‌eamesii P.M. Brown is a rare ladies’-tresses hybrid in New England that is known from CT (it has also been reported from other southern New England states, but specimens are unknown), where it usually grows with both parents. It has a white labellum with green-yellow tinting on the labellum (those of S. tuberosa are pure white), usually 2 white, narrow-conical roots, and lacks leaves during anthesis (similar 
to both parents). The flowers are intermediate in size between the parents (4–7.5 mm long is S. lacera var. gracilis and 3–5.5 mm long in S. tuberosa).

3a×8.  Spiranthes ×‌intermedia Ames is a very rare ladies’-tresses hybrid in New England that is known from southeastern MA. It is similar to Spiranthes vernalis except that the pubescence of the inflorescence is slightly expanded apically into a slender gland (vs. pointed at apex) and the lateral petals show two primary veins, one of which usually branching to create three veins distally (vs. usually three mains originating from the base of each lateral petal). Spiranthes lacera var. gracilis shows stipitate-glands in the inflorescence and usually two unbranched veins on the lateral petals. Spiranthes ×‌intermedia is further characterized by yellow-green coloration along the center of the labellum that may become more yellow near the apex and a stipitate column (similar 
to S. vernalis).