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Cypripedium parviflorum — yellow lady's-slipper

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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

Yellow lady's-slipper is very variable in appearance, and three varieties are recognized in New England. It has been used by Native Americans and modern herbalists to treat ailments such as anxiety, insomnia, and depression. It is illegal to harvest wild plants in New England, where it is protected, but it can be cultivated relatively easily.

Habitat

Anthropogenic (man-made or disturbed habitats), fens, forests, riverine (in rivers or streams), shores of rivers or lakes, shrublands or thickets, swamps, wetland margins (edges of wetlands), woodlands

Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf arrangement
alternate: there is one leaf per node along the stem
Number of leaves on stem
  • five
  • four
  • three
  • two
Form of lower petal
the labellum has a pouch-like shape
Lower petal outline
the labellum is simple in form
Main color of lower petal
  • white
  • yellow
Nectar spur
there are no nectar spurs on the flower
Inflorescence type
  • the inflorescence has only one flower or a pair of flowers on it
  • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
Lower petal characteristics
  • the labellum is in the shape of a pouch
  • the labellum is simple in form
Lower petal length
15–54 mm
Sepal length
11–80 mm
Show all characteristics

  • Flowers

    Flower petal color
    • brown
    • green
    • purple
    • red
    • yellow
    Flower symmetry
    there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
    Flowering date
    • June
    • May
    Flowers per inflorescence
    1–3
    Form of lower petal
    the labellum has a pouch-like shape
    Hairs on inflorescence axis
    • NA
    • at least some of the hairs on the main stem of the inflorescence have glands
    • the main stem of the inflorescence has hairs entirely without glands
    Inflorescence type
    • the inflorescence has only one flower or a pair of flowers on 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 narrowed base of lower petal
    0 mm
    Lobes at base of lower petal
    0 mm
    Lower petal characteristics
    • the labellum is in the shape of a pouch
    • the labellum is simple in form
    Lower petal length
    15–54 mm
    Lower petal outline
    the labellum is simple in form
    Lower petal strongly red-veined
    no
    Main color of lower petal
    • white
    • yellow
    Nectar spur
    there are no nectar spurs on the flower
    Nectar spur length
    0 mm
    Number of stamens
    2
    Orientation of side petals
    • the lateral petals slant outward
    • the lateral petals slant somewhat downward
    Pollen sacs
    NA
    Self-pollinating flowers
    there are no cleistogamous flowers on this plant
    Sepal length
    11–80 mm
    Sepals fused only to sepals
    the sepals are fused to each other (not other flower parts), at least near their bases
    Shape of viscidium
    NA
    Spots on lower petal
    • no
    • yes
    Spur opening membrane
    NA
    Spur opening shape
    NA

  • Fruits or seeds

    Fruit length
    2.6–3.7 mm
    Fruit width
    1–2 mm
    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 longer than the associated flower
    • the bract is shorter than the associated flower
    Features of leaves
    • the leaf does not have any of the mentioned special features
    • the leaf is pleated or folded back and forth along its length
    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
    52–209 mm
    Leaf blade length to width ratio
    1.5–3.3
    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 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)
    Leaf blade width
    16–143 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
    • five
    • four
    • three
    • two

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of wetlands
    • fens
    • forests
    • in rivers or streams
    • man-made or disturbed habitats
    • shores of rivers or lakes
    • shrublands or thickets
    • swamps
    • 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.

Connecticut
uncommon (S-rank: S3), special concern (code: SC)

var. makasin

Connecticut
unrankable (S-rank: SU)
Massachusetts
extremely rare (S-rank: S1), endangered (code: E)
New Hampshire
extremely rare (S-rank: S1), endangered (code: E)
Vermont
rare to uncommon (S-rank: S2S3)

var. parviflorum

Connecticut
unranked (S-rank: SNR)
Massachusetts
historical (S-rank: SH)
Rhode Island
historical (S-rank: SH), state historical (code: SH)

var. pubescens

Connecticut
unrankable (S-rank: SU)
Maine
unranked (S-rank: SNR)
Massachusetts
rare to uncommon (S-rank: S2S3)
New Hampshire
rare (S-rank: S2), threatened (code: T)
Rhode Island
extremely rare (S-rank: S1), state endangered (code: SE)
Vermont
uncommon (S-rank: S3)

Native to North America?

Yes

Synonyms

  • Cypripedium calceolus L. var. pubescens (Willd.) Correll
  • Cypripedium pubescens Willd.

Family

Orchidaceae

Genus

Cypripedium

Notes on subspecies and varieties in New England

Variety pubescens is known from CT, MA, ME, NH, RI, VT. Variety parviflorum is known from CT, MA, RI, VT. Variety makasin is known from CT, MA, ME, NH, VT. Both var. makasin and var. parviflorum are of regional conservation concern.

Help

From the dichotomous key of Flora Novae Angliae

3.  Cypripedium parviflorum Salisb. NC

yellow lady’s-slipper. 3a. Cypripedium calceolus L. var. pubescens (Willd.) Correll; 
C. pubescens Willd.;  3b. Cypripedium calceolus L. var. parviflorum (Salisb.) Fern.; 3c. Cypripedium makasin Farw. • CT, MA, ME, NH, ri, VT. Evergreen swamps, deciduous forests, river banks, river shore ledges.

1a.  Labellum usually 3–5.4 cm long; lateral petals mostly 5–8 cm long, entirely yellow-green 
or sparsely to moderately spotted or streaked with red-purple [Fig. 164] … 3a. C. parviflorum var. pubescens (Willd.) Knight

1b.  Labellum 1.5–3 (–3.5) cm long; lateral petals mostly 3–5 cm long, either densely spotted or evenly suffused with red-purple or red-brown [Fig. 163]

2a.  Uppermost sheathing bract at base of stem conspicuously pubescent with short hairs; red-purple color of lateral petals composed of numerous, densely spaced dots; floral scent rose-like or musty; plants of deciduous forests … 3b. C. parviflorum var. parviflorum

2b.  Uppermost sheathing bract glabrous or inconspicuously pubescent; red-purple color of lateral petals due to an even suffusion of pigment; floral scent intensely sweet; plants of high-pH wetlands and shores … 3c. C. parviflorum var. makasin (Farw.) Sheviak

Variety pubescens is known from CT, MA, ME, NH, RI, VT. Variety parviflorum is known from CT, MA, RI, VT. Variety makasin is known from CT, MA, ME, NH, VT. Both var. makasin and var. parviflorum are of regional conservation concern. Sheviak (1993, 1994) divided the small-flowered yellow lady’s-slippers into two varieties based on ecology and floral morphology and fragrance—var. makasin and var. parviflorum. Cypripedium parviflorum var. pubescens is a problematic taxon in New England and has been frequently misidentified. This is, in part, due to a belief that it occurred exclusively in deciduous forests. Though this holds true for the majority of occurrences in southern New England, var. pubescens is frequently located in evergreen swamps dominated by Thuja occidentalis (and rarely shaded river shore ledges) in northern New England. These plants of var. pubescens from wetlands show glabrous sheathing bracts, which is in contradiction to the statements of Sheviak (2002a), suggesting this character to be environmentally influenced. Variety pubescens has a musty floral fragrance similar to var. parviflorum.