Cypripedium parviflorum

• 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]}