Corallorhiza wisteriana Conrad
Family - Orchidaceae
Habit - Perennial, saprophytic, lacking visible amounts of chlorophyll, glabrous, with highly branched, coral-like rhizomes encircled at regular intervals by scars of successive sheathing bracts.
Stems - Flowering stems to 35 mm, glabrous, brownish or purplish.
Leaves - Absent. Small sheathing bracts present on lower flowering stems.
Inflorescences - Racemes with 8-20 flowers.
Terminal flower buds.
Flowers - Zygomorphic, perfect. Sepals and lateral petals 6-8 mm long, greenish purple, curved upward and inward and partially overlapping the upper sepal. Lip ovate to obovate, 5-6 mm long, with wavy margins, white with reddish purple spots. Stamens 1, staminodes absent. Ovary 1, unilocular.
Fruits - Capsules 8-12 mm long, strongly ribbed, pendent.
Flowering - April - May.
Habitat - Rich forests, often on acidic substrate, glade margins.
Origin - Native to the U.S.
Lookalikes - Corallorhiza odontorhiza; more distantly, Listera.
Other info. - Like many of Missouri's orchids, this one is relatively inconspicuous with small flowers and brownish stems which tend to blend in visually with surrounding leaf litter. It is found across most of Missouri, though is apparently uncommon in the northern third of the state. Its U.S. distribution comprises two distinct bands, one (which includes Missouri) in the southeastern quadrant, the other running from central Montana down through Arizona and New Mexico. Corallorhiza wisteriana is one of two species of the genus found in Missouri. The other (C. odontoriza) has smaller flowers, which are usually cleistogamous, and blooms in the fall.
Photographs taken at Weldon Spring Conservation Area, St. Charles County, MO, 5-4-2011, and at Matson Hill County Park, St. Charles County, MO, 4-29-2015 (SRTurner).