Spiranthes - Ladies' Tresses

by
Monica Gupta
 
 
Courtesy, UGA Herbarium


"It was a cool January 1 in The Woodlands, Texas.  As my grandaughters and I walked to the playground, a small flower stood protected under the trees and, as usual, one of the girls asked me to give it a name.  Although she was only ten years old, her list of flower names was becoming as long as a list of her neighborhood friends.  When we all put our heads to the ground, I said 'Orchid?-at this time of the year?-in this part of the world?'  It was called ladies' tresses, and it really was an orchid!  I feel that my grandaughters will remember forever our surprise and that an orchid can be very beautiful, whether large or small, whether colorful or white, and standing alone under a playground tree" (Bulat & Bulat, 1995).
 
 Table of Contents
 
Etymology: Spiranthes = "Spiraled blossom" (Chapman, 1997)

Higher Taxon               (Mabberley, 1987)
    Family:  Orchidaceae

 
Description
    According to Duncan and Foote, Spiranthes is "a variable genus, with plants often difficult to name to species.  The generic name means 'coil flower' in allusion to the spiral arrangement of the flowers of many species"(Duncan & Foote, 1975).
    Fanfani and Rossi describe the genus Spiranthes to be,

Medium-small terrestrial plants with fibrous or tuberous roots.  Approximately 300 species are ascribed to this somewhat polymorphous genus, although its precise character is still a source of systematic controversy.  The leaves, variable in shape, are as a rule arranged in the form of a basal rosette; they are either persistent or caducous, present or absent during flowering, sometimes bractiform.  The stiff, erect, fairly long inflorescence is composed of numerous tubular flowers that are quite small.  These vary in color although they are usually greenish-white and arranged in a spiral.  These lants grow freely in fields, meadows and savannas but are also found in woods and forests, both on acid and calcareous soil (Fanfani & Rossi, 1988).
 
Species List
    There are approximately thirty species in this genus, most of them being native to North and Central America (Davies & Huxley, 1983).  Scientific names and common names of species of the genus Spiranthes are listed below.  Hybrids are quite rare in this genus since members do not freely cross with each other, so they are not of much concern (Chapman, 1997).

S. aestivalis - Summer Ladies' Tresses
S. casei - Case's Ladies' Tresses
S. cernua - Nodding Ladies' Tresses
S. gracilis - Slender Ladies' Tresses
S. grayi - Little Ladies' Tresses
S. lacera - Slender Ladies' Tresses
S. lucida - Shining Ladies' Tresses
S. laciniata - Lace-lip Ladies' Tresses
S. longilabris - Long-lip Ladies' Tresses
S. magnicamporum - Great Plains Ladies' Tresses
S. ochroleuca - Yellow Nodding Ladies' Tresses
S. ovalis - Oval Ladies' Tresses
S. praecox - Grass-leaved Ladies' Tresses
S. romanzoffiana - Hooded Ladies' Tresses
S. sinensis - Pink Ladies' Tresses
S. spiralis - Autumn Ladies' Tresses
S. tuberosa - Beck's Tresses
S. vernalis - Spring Ladies' Tresses

This list was compiled from a number of sources (Chapman, 1997)  (Gupton & Swope, 1986)  (Davies & Huxley, 1983) (Smith, 1993).  Gupton and Swope list nine species, Chapman lists five, Davies and Huxley list three, and Smith lists one.
 

Identification Guide
    One major characteristic of this genus is the confusing similarity that exists between the species (Chapman, 1997).  Included below is a key to assist in species identification however Chapman gives some words of caution: "any key to this genus automatically will be flawed by the nature of the orchids observed.  Every characteristic used here is variable to some degree, and those attributes that are described must be understood to represent the majority of specimens existing in their preferred habitats"(Chapman, 1997).

Just as the key that follows, most Spiranthes keys are usually based on whether the flowers are single-ranked or multi-ranked on the stem (Chapman, 1997).
 
Key to Spiranthes: Please see extended key in Chapman's, Orchids of the Northeast       p.69-70 (Chapman, 1997).

S. cernua has slender long leaves with a distinct base, most growing from the base of the stem.  The lip is typically white to white with a yellowish center (Chapman, 1997).
"This species has several spirals forming a dense spike with flowers usually in 3 longitudinal rows.  The lip is 6-14 mm long and has 2 small rounded projections at its base.  The longest leaves are near the base of the stem and at most are 25 cm long" (Duncan & Foote, 1975).

S. vernalis has basal and erect leaves, up to 30 cm long and 1 cm wide.  Their upper parts tend to be covered with fine dense pointed hairs.  The stem, ovulary, and bracts are densely and finely hairy (glandless hairs).  The flowers are strongly spiraled and the lip is usually 4.5 - 8 mm long, and widest near the base (Duncan & Foote, 1975).
 

General Information
    Spiranthes has a nearly continuous distribution around the Northern Hemisphere.  Most species are mobile and tend to have weed-like tendencies.  For example, many species of Spiranthes are scarce and localized in undisturbed areas but grow in plethora in disturbed areas - colonizers. (Dressler, 1981)
 

References

Mabberley, D.J.  1987.  The Plant Book.  Cambridge University Press.  Cambridge, Massachusetts.

Fanfani, Alberto and Walter Rossi.  1988.  Simon & Schuster's Guide to Orchids.  Simon & Schuster Inc.  New York, New York.

Gupton, Oscar W. and Fred C. Swope.  1986.  Wild Orchids of the Middle Atlantic States.  University of Tennessee Press.  Knoxville, Tennessee.

Chapman, William K.  1997.  Orchids of the Northeast - A Field Guide.  Syracuse University Press.  Syracuse, New York.

Davies, Paule & Jenne, and Anthony Huxley.  1983.  Wild Orchids of Britain and Europe.  Chatto & Windus - The Hogarth Press.  London, England.

Dressler, Robert L. 1981.  The Orchids - Natural History and Classification.  Harvard University Press.  Cambridge, Massachusetts & London, England.

Cullen, J.  1992.  The Orchid Book:  A guide to the identification of cultivated orchid species.  Cambridge University Press.  Cambridge.

Bulat, Thomas J. and Marilyn Bulat.  1995.  Hidden Orchids.  Rudi Publishing.  Iowa City.

Duncan, Wilbur H. and Leonard E. Foote.  1975.  Wildflowers of the Southeastern United States.  University of Georgia Press.  Athens, Georgia.

Smith, Welby R.  1993.  Orchids of Minnesota.  University of Minnesota Press.  Minneapolis, Minnesota.

University of Georgia Herbarium, Athens, Georgia.
 
Cronquist, Arthur. 1981. An Integrated System of Classification of Flowering Plants.  Columbia University Press.  New York.

Jones, Samuel B. Jr., and Nancy Craft Coile.  1988. The Distribution of the Vascular Flora of Georgia.  Dept. of Botany. University of Georgia. Athens, Georgia.

Chester, Edward, B. Eugene Wafford, Robert Kral, Hal R. Deselam, A. Murray Evans. 1993.  Atlas of Tennessee Vascular Plants.  Austin Peay State University.  Clarksville, Tennessee.

Acknowledgements
    Many thanks to:
        - Patrick Sweeney & Mike Moore for orienting me to the UGA Herbarium.
        - UGA Herbarium for providing me with slides and reference books.
        - Beth Shapiro for scanning my slides for my page.
        - Elizabeth Skillen for answering ALL my silly questions.
        - Anupam Jaju for assisting me in my web page design.

 
 
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