Yellow Lady's Slipper (Cypripedium parviflorum)

Cypripedium parviflorum
Cypripedium parviflorum var. makasin Mackinac Island, Michigan
Conservation status
Least Concern  (IUCN 3.1)[1]
Secure  (NatureServe)[2]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Cypripedioideae
Genus:	Cypripedium
Species:	C. parviflorum
Binomial name
Cypripedium parviflorum Salisb.
Varieties[3]
C. p. var. exiliens C. p. var. makasin C. p. var. parviflorum C. p. var. pubescens
Synonyms[3]
List Calceolus parviflorus (Salisb.) Nieuwl. Criosanthes parviflora (Salisb.) Raf. Cypripedium bulbosum var. parviflorum (Salisb.) Farw. Cypripedium calceolus subsp. parviflorum (Salisb.) Hultén Cypripedium calceolus var. parviflorum (Salisb.) Fernald Cypripedium hirsutum var. parviflorum (Salisb.) Rolfe Cypripedium luteum var. parviflorum (Salisb.) Raf.

Cypripedium parviflorum, commonly known as yellow lady's slipper^[4] or moccasin flower,^[5] is a lady's slipper orchid native to North America.^[6] It is widespread, ranging from Alaska south to Arizona and Georgia.^[7] It grows in fens, wetlands, shorelines, and damp woodlands.^[8]

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• Plant: 16 to 60 cm tall, reported to 80 cm elsewhere: stem, bracts, and leaves pubescent; flower stem rises 10 cm above leaves; one flower, rarely two.
• Roots: few to many slender roots to 4 cm long on jointed rhizome.
• Leaves: ovate lanceolate, cauline, plicate, four to six on blooming plants, from 9 ⨉ 4 cm to 14 ⨉ 5 cm; covered with fine hairs on underside; a few hairs on topside.
• Floral bracts: ovate lanceolate bract at base of ovary, 7 ⨉ 2 cm.
• Flowers: bright yellow pouch with greenish to reddish sepals and petals; up to 10 cm high ⨉ 10 cm wide.
• Sepals: yellowish green with reddish stripes that turn to dots near pouch, fine hairs on back and edges; dorsal sepal ovate lanceolate, slightly concave, 4 ⨉ 2.2 cm; synsepal ellipitic, slightly concave; slight notch at tip, 3.2 ⨉ 1.4 cm.
• Petals: linear, acute, yellowish green with reddish stripes that turn to dots at pouch; 5.5 cm long ⨉ 0.7 cm wide; fine hairs on back along well-defined central ridge; few hairs on inner one-third toward pouch.
• Lip: bright yellow obovoid (pouch- or slipper-shaped), 3.2 cm wide ⨉ 4.0 cm high; opening 1.2 ⨉ 2.0 cm, with incurved margin; red dotted stripes on veins and faint reddish dots on inside and back of pouch.
• Column: light green with red dots at base, 1.5 cm high; two fertile anthers, one to either side; staminode yellow with red dots, arrowhead-shaped, with V form (folded); pollinia yellow sticky masses.
• Capsule: ellipsoidal, pubescent, 2.2 to 3 cm long ⨉ 0.6 to 1.3 cm in diameter

Cypripedium parviflorum was given its scientific name in 1791 by Richard Anthony Salisbury. It is classified as part of the genus Cypripedium as part of the family Orchidaceae.^[3] C. parviflorum is a highly variable species, which is a result of both hybridization and phenotypic plasticity.^[9]

Four varieties are widely recognized. They are:^[10][3]

• C. parviflorum var. exiliens Sheviak – Alaska
• C. parviflorum var. makasin (Farwell) Sheviak – commonly called the "northern yellow lady's-slipper";^[11] widely distributed over much of Canada and the northern United States
• C. parviflorum var. parviflorum – commonly called the "small yellow lady's-slipper";^[12] southern part of the species range, from eastern Nebraska and eastern Oklahoma east to Virginia and New Hampshire
• C. parviflorum var. pubescens (Willdenow) O. W. Knight – commonly called the "large yellow lady's-slipper";^[12] very widespread across much of United States, Canada, and St. Pierre & Miquelon; treated by many authors as a distinct species, Cypripedium pubescens

• 
  C. parviflorum var. parviflorum, showing pubescent bract and dark maroon sepals
• 
  C. parviflorum var. pubescens, showing yellow-green sepals spotted with maroon

Cypripedium parviflorum has 36 synonyms of the species or three of its four varieties.^{[3][13][14][15]}

• Newfoundland to British-Columbia, south to Georgia, Arizona, and Washington; Europe.
• Newfoundland to Alaska and south to Oregon in the West.
• In the East along the Atlantic Coast, it is in every state except Florida and extends across to Louisiana and eastern Texas.
• New Mexico state: Catron, Colfax, Grant, Los Alamos, Otero, San Miguel, San Juan and Santa Fe Counties.
• Arizona state: Apache, Graham, and Greenlee Counties.

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C. parviflorum is a more upland plant preferring subacidic to neutral soils. It is found primarily in mesic to dry-mesic upland forests, woodlands with deep humus or layers of leaf litter and shaded boggy habitats, but also in hill prairies and occasionally in wetlands with organic, well-drained, sandy soils. Specifically, in fir, pine, and aspen forest between 6,000 and 9,500 feet (1,800 and 2,900 m), it prefers moderate shade to nearly full sun. It may be present in mountain meadows and on timbered slopes, as well as dripping seeps on steep to moderately sloped canyon walls.

• Media related to Cypripedium parviflorum at Wikimedia Commons
• Data related to Cypripedium parviflorum at Wikispecies

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