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Quayle Report - Jeff Quayle
November 2003


Plant of the Month

Spiranthes magnicamporum

Great Plains Ladies'-Tresses

One of our uncommon native orchids, the Great Plains Ladies'-Tresses (Spiranthes magnicamporum), blooms in our area from September to November. Flowers are bright white, with a fragrant scent, similar to vanilla. They occur on upland calcareous soils in prairies locally in Cooke, Grayson, Montague, Parker, and Tarrant counties. Flowers appear slender with spreading sepals as compared to Nodding Ladies'-Tresses (S. cernua) with inflated tubular flowers and appressed sepals. Sheviak (1982) indicated that while introgression occurs between S. magnicamporum and S. cernua, they differ in chromosome number, are partially genetically isolated, and both species have different ecological requirements. S. cernua is usually found in prairies and open woods in sandy soils. S. magnicamporum is usually found in upland prairies on calcareous soils, usually associated with limestone seeps. They are usually found growing in association with Seep Muhly (Muhlenbergia reverchonii), Little Bluestem (Schizachyrium scoparium), and Indiangrass (Sorghastrum nutans). According to Liggio (1999), S. magnicamporum was first described as a new species by Charles Sheviak in 1973. It was once considered a variety of S. cernua, but is now recognized as both a separate species and a member of the Spiranthes cernua complex (S. magnicamporum, S. cernua, S. odorata). Older herbarium specimens of S. cernua may actually be S. magnicamporum. However, many of the characteristics that distinquish S. magnicamporum from S. cernua in living plants are lost in the preparation of herbarium specimens, making correct identification difficult (Sheviak 1982).

Spiranthes magnicamporum can be found at the Fort Worth Nature Center (near Greer Island), Stella Rowan Prairie, and Spring Creek Forest Preserve.

Book recommendation:
Wild Orchids of Texas, by Joe Liggio (1999) - University of Texas Press - retails for $29.95 ($20.97 at www.amazon.com)


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