Nebraskaland

12 Nebraskaland • October 2019 PHOTO BY GERRY STEINAUER IN THE FIELD The Ute ladies'-tresses (Spiranthes diluvialis) is an eloquent little orchid with an intriguing name. The word "Ute" because the plant occurs within the historic range of the Ute Tribe in Colorado and Utah. The word "tresses" because the many small, ivory-colored flowers, arranged in spirals on the flowering spike, resemble the braids (tresses) of a woman's hair. Listed as both a state and federally threatened species, this rare, late-summer blooming perennial has a limited range in Nebraska. A thousand or so individuals grow only in alkaline wet meadows along a two-mile stretch of the upper Niobrara River Valley in Sioux County. Range-wide, the Ute ladies'-tresses has populations scattered over the northwestern United States and southern British Columbia where it grows in old oxbows, gravel bars, wet meadows and seeps at elevations ranging from 4,300 to 7,000 feet. The Nebraska population is its easternmost location. The orchid was discovered in Nebraska in 1996 when a botanist surveying for the plant in Wyoming's Niobrara Valley wandered across the border. In 1997, hoping to find more populations, the Nebraska Game and Parks surveyed alkaline and some freshwater meadows throughout the Panhandle. No other Ute ladies'-tresses were discovered. We did find the nodding ladies'-tresses (S. cernua) growing in western Sandhills alkaline meadows and the uncommon Great Plains ladies-tressses (S. magnicamporum) in one alkaline meadow in the upper Pumpkin Creek Valley in Scotts Bluff County. Several factors may explain the Ute and other ladies'- tresses' sporadic distribution in Nebraska and range-wide. For one, the orchids' microscopic seeds can be wind-blown for great distances allowing establishment in isolated locations. In addition, ladies'-tresses form associations with mycorrihzal soil fungi that infect the roots and aid in nutrient and water uptake. In return, the orchids supply the fungi with carbohydrates through photosynthesis. The tiny orchid seeds, which lack endosperm (starch supply), are especially dependent on fungal infection for germination and growth. In short, the orchids can grow only in habitats also suitable for their needed fungi. The Ute ladies'-tresses' distribution is also likely limited by habitat management. In Nebraska, the plant grows in meadows that are hayed or grazed in early summer (June through mid-July). In late-summer hayed or grazed meadows, the cutting or nipping of the orchid's flower stalks prevent seed production, which over time, would threaten its survival at such sites. Being at the extreme of the Ute ladies'-tresses range reduces the odds that we will discover other populations of the plant in western Nebraska. Adding to the difficulty, it is a big landscape to survey for such a small orchid that is choosey about its habitat. By Gerry Steinauer THREATENED AND ENDANGERED: THE UTE LADIES'-TRESSES

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