Cypripedium parviflorum Salisb.

Yellow Lady's Slipper Orchid

© SRTurner

Family - Orchidaceae

Habit - Rhizomatous perennial forb, often colonial.

Stems - Ascending to erect, to 80 cm, usually densely hairy.

Leaves - Alternate, simple, entire, sessile, 3-6 per flowering stem, 14-20 cm long, more than 4 cm wide, ovate to elliptic, somewhat ribbed or corrugated, hairy.

	Stem and leaves.
© SRTurner

	Leaf, adaxial.
© SRTurner

Inflorescence - One or two terminal flowers, each subtended by a leafy bract.

	Inflorescence.
© SRTurner

	Sepals and bract.
© SRTurner

Flowers - Sepals 2-5 cm long, ovate-lanceolate, undulate or somewhat spirally twisted, yellowish green or reddish purple to brown. Lateral petals spreading, in some species somewhat downward arching or drooping, 3-9 cm long, longer than the lip, linear-lanceolate, spirally twisted, yellowish green or reddish purple to brown. Lip 2-5 cm long, obovoid, the margins rolled inward along the edge of the opening, yellow (rarely white), usually with red spots on the inside surface and around the opening. Column 15-25 mm long, the staminode triangular, yellow with red spots. Lateral petals . Lip enlarged to form a slipperlike pouch. Column with 2 stamens on either side near the tip, the tip with a large, ovate to triangular staminode.

	Flower.
© DETenaglia

	Flower.
© SRTurner

	Flower.
© SRTurner

	Flower.
© SRTurner

Flowering - April - June.

Habitat - North and East-facing slopes of ravines, mesic, upland woods.

Origin - Native to U.S., Europe, and Asia.

Other info. - This showy and striking species can be found throughout Missouri. The plant is just one of a larger complex of plants which occur in Europe, Asia, and North America. At present, two varieties are recognized in Missouri. Variety parviflorum has a corolla lip 2-3 cm long, and 4-6 leaves per flowering stem. Variety pubescens (Willd.) O.W. Knight has a corolla lip 3-6 cm long and 3-4 leaves per flowering stem. Both varieties are commonly scattered throughout the state, and the set of images above may include both varieties. A rare white form of var. parviflorum has been collected in Missouri in a couple of southern counties. The species was long known as C. calceolus, with this epithet also applied to the varieties.

Due to its beauty, the plant has sometimes been dug from the wild for use in gardens. This practice, followed by disreputable nurseries, as well as collection of the roots for various putative medicinal purposes, has led to declines in wild populations. Plants propagated responsibly from seed are increasingly available from nurseries which ethically support native plant gardening.

Photographs taken in Linville, NC., 4-30-03 (DETenaglia); also at Daniel Boone Conservation Area, Warren County, MO, 5-17-2008, and St. Joe State Park, St. Francois County, MO, 5-13-2015 and 5-15-2017 (SRTurner).