1997-06-13_REPORT - M1981302 (11)

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PART I INTRODUCTION The Ute ladies'-tresses (Soiranthes diluvialis) was listed as a threatened species on January 17, 1992 (57 FR 2053) under the authority of the Endangered Species Act of 1973 (Act) , as amended. The U.S. Fish and Wildlife Service (Service) is responsible for preparing a recovery plan and guiding actions that will restore populations and remove threats such that the species no longer requires protection under the Act and can be removed from the list of threatened species. This recovery plan describes recovery goals and discusses how they may be achieved so that the Ute ladies'-tresses can be removed from the list of threatened plants. A. Description S. diluvialis is a perennial , terrestrial orchid with stems 20 to 50 cm (8 to 20 inches) tall , arising from tuberously thickened roots. Its narrow (1.0 cm ( .39 inches)) leaves can reach 28 cm (11 inches) long. Basal leaves are longest and become reduced in size up the stem. The flowers consist of few to many small white or ivory flowers clustered into a spike arrangement at the top of the stem. The species is characterized by whitish, stout, ringent (gaping at the mouth) flowers. The sepals and petals, except for the lip are rather straight, although the lateral sepals are variably oriented, these often spreading abruptly from the base of the flower; sepals are free to the base. The rachis is pubescent with the longest trichomes 0.2 mm (0.008 inches) long or longer, usually much longer. It blooms, generally, from late July through August. However, depending on location and climatic conditions, Ute ladies'-tresses may bloom in early July or may still be in flower as late as early October. B. Taxonomy Prior to the description of S. diluvialis in 1984, workers in Orchidaceae had tried to accommodate specimens from the West in three taxa of white-flowered $eiranthes orchids: Soiranthes cernua L.C. Richard, Spiranthes romanzoffiana Chamisso, and Soiranthes oorrifolia Lindley. In 1980, a specimen of Soiranthes was collected near Golden, Colorado, that appeared to be S. cernua. In 1981, live plants were collected at that site and sent to Dr. Charles J. Sheviak, who initiated studies on the genus Soiranthes in the early 1970's, for examination. In 1982 and 1983, Dr. Sheviak visited Colorado and Utah. After examining herbarium specimens and live specimens in the field and after cytologic study, Dr. Sheviak was convinced that the Colorado-Utah plants were a new species, which he described in 1984 (Sheviak 1984) . The type locality is along Clear Creek west of Golden. In his original description, Sheviak (1984) suggested that S. diluvialis resulted from the hybridization of Soiranthes maanicamporum and S. romanzoffiana during a Pleistocene pluvial period when the region supported lush grasslands and the two parent species would have been sympatric or parapatric. Under a cooler and wetter climate, S. romanzoffiana would have 1