Nebraskaland

12 Nebraskaland • November 2019 IN THE FIELD PHOTO BY GERRY STEINAUER The western prairie fringed orchid (Platanthera praeclara) historically grew in moist tallgrass prairies and wet meadows ranging from southern Manitoba south to Oklahoma, including much of the eastern half of Nebraska. European settlement, however, had an immediate impact on this sensitive species. An 1889 account from Kansas stated that "once school children brought armfuls of the curious [orchid to their teachers] … now they are seldom seen." An 1898 Nebraska account notes the orchid "was common in wet valleys of the sandhills … also in [the tallgrass prairie region], where, however, it is a disappearing species." Since then, loss of its prairie habitat, heavy livestock grazing, herbicides and invasive plants have stressed the plant to the point where it is now listed as both federally and state threatened. The perennial orchid begins growth in early May and the plant commonly reaches heights of 20 to 30 inches. Its 3- to 5-inch-long leaves are somewhat thickened with prominent parallel veins. The lower lip of the large creamy white to greenish flower is divided into three feathered lobes with the other smaller petals and sepals forming a hood above. An up to 2-inch-long nectar spur extends back from the lower petal. The few to up to 25 flowers that occur along the elongate inflorescence begin blooming in mid-June to early July, depending on weather and location, with southern plants flowering first. The specialized flowers are designed for one purpose: pollination by a few select species of nocturnal hawkmoths (sphinx moths). Near dusk, the orchids release a sweet fragrance to attract the wide-ranging moths. The white- fringed lip directs the moths to the spur with its rich nectar deep within. The moth, while hovering in front of the flower with its long tongue extended to feed, brushes against two pollen-bearing structures called columns. At this moment, two sticky balls of pollen become glued to the moth's eyes or head. When the moth leaves the flower, the columns rotate, exposing the stigma (receptive female structure) for pollination by a next visiting, pollen-carrying moth. A decline in hawkmoths may be another reason for the decline in orchid populations. In 2012, the Nebraska Game and Parks Commission resurveyed 65 prairies in eastern Nebraska and the Sandhills where over the last few decades a total of 1,385 western prairie fringed orchids were observed during prior surveys. We found a total of 595 plants at only 21 (32 percent) of the sites. For the record, 2012 was a particularly droughty year, and individual orchid plants may not flower in such stressful years. Instead, these vegetative plants either do not produce above ground growth or send up only one or two basal leafs, which when concealed among the prairie grasses, are nearly impossible to detect during surveys. The sharp decline of the western prairie fringed orchid in Nebraska's tallgrass region in recent decades is distressing. Hopefully, healthy populations of this beautiful and intriguing species can be maintained in the semi-wilds of the Sandhills. Gerry Steinauer is a botanist for the Nebraska Game and Parks Commission. By Gerry Steinauer THREATENED AND ENDANGERED: THE WESTERN PRAIRIE FRINGED ORCHID

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