Spiranthes L. C. Rich.
The Ladies'-tresses orchids
Spiranthes cernua, Nodding Ladies'-tresses
The name Spiranthes
is derived from the Greek for coiled ("spir") flowers ("anthes"),
an allusion to the typically spiralled arrangement of the inflorescence.
Taxonomic delimitation of the genus is very unclear, with the best estimate
of size being approximately 300 species worldwide. Wisconsin, however, is
home to only six species. These can be difficult to distinguish from each
other, but with practice, they can be reliably determined from fresh material.
A. Labellum small (3.5-6 mm)
AA. Labellum longer (6-12 mm)
- Inflorescence single-ranked; leaves basal, ovate; labellum bearing a
- Inflorescence several-ranked; leaves linear-lanceolate; labellum white...ovalis
B. Labellum pandurate (fiddle-shaped)...romanzoffiana
BB. Labellum not pandurate
C.Leaves absent at flowering; lateral sepals spreading; flowers
typically strongly fragrant...magnicamporum
CC.At least some leaves typically present at flowering
- Flowers cream-colored; dorsal sepals and petals directed forward,
making the flowers appear closed; lower leaves often withered at anthesis;
typically growing in dry sites...casei
- Flowers typically white, appearing more "open" than the
preceding species; leaves usually present at anthesis; a plant of moist
One species that should be looked for in Wisconsin is Spiranthes
lucida. It is found in Michigan, Illinois, and Iowa, not far from
suitable habitat in Wisconsin. About 15 years ago, Don Henson collected
S. lucida on the Michigan side of the Menominee River, placing lucida
within meters of Wisconsin. This species should be diligently searched
for in fens and along stream and river banks, particularly those flowing
through areas of calcareous substrate.
Go to the list
of the species of Spiranthes.
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