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Insect pollination of the endangered monkey-face Orchid (platanthera integrilabia) in McMinn County, Tennessee - One last glimpse of a once common spectacle

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Abstract

The Monkey-face Orchid, Platanthera integrilabia, was locally common on the Cumberland Plateau of Kentucky and Tennessee prior to the 1940s, but is currently a C2 candidate for United States protection as an endangered species. Insect pollination of this orchid is described for the first time at the largest remaining population of the species, located in McMinn County, Tennessee, just prior to peak flowering (12-15 August 1992). Despite the orchid having flowers adapted to moth pollination, three day-flying Lepidoptera (Epargyreus clarus, Papilio glacus, and P. troilus) carried pollinia on compound eyes and were pollinators. Over half of all flowers (624 of 1,096 or 56.9%) set fruit two months after flowering. A mean of 4.7 capsules per inflorescence and 3,433 seeds per capsule were recorded. The survival of P. integrilabia will likely depend on the continued existence of the McMinn County population as a seed source for a vigorous program to reestablish seedlings in suitable habitats.
... Although the habitat requirements of P. integrilabia may not be as specific as historically reported, which could complicate assessments of its habitat suitability and plans for habitat management, habitat loss due to anthropogenic activities including development and silvicultural practices has been cited as a primary threat to this species [28]. Biotic interactions including whitetailed deer (Odocoileus virginianus) herbivory, feral hog (Sus scrofa) activity [28,35], encroachment and competition from invasive nonnative plant species [35], pollination inconsistencies [36], and mycorrhizal dependence [37][38][39] also are considered to be significant concerns [28]. The success of efforts to establish new populations of rare species depends on knowing not only their habitat requirements but also how concurrent biotic interactions-especially negative interactions with herbivores or natural enemies-that are likely in restoration sites could influence those species [40]. ...
... Because appropriate symbiotic mycorrhizal fungi and pollinator species are necessary for the completion of orchid life cycles [70], and thus, ultimately, fitness, consideration of such interactions is important to the success of orchid translocations [55,56]. Both specific fungal symbiont and pollinator species associated with P. integrilabia have been identified [36,39], and we suggest that these biotic interactions be considered in site selection for future translocation efforts. In addition to more comprehensive site assessments, the success of terrestrial orchid translocation also could be improved by further considerations of the propagules to be used. ...
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Translocation is increasingly being used to supplement existing occurrences and establish new occurrences of rare plant species, but translocation success is dependent on understanding responses to habitat conditions and management. Platanthera integrilabia (white fringeless orchid) is a rare terrestrial orchid species presently found in mostly small occurrences that comprise a fraction of its historical distribution and abundance in the southeastern United States. We investigated the influence of shade and white-tailed deer herbivory, as cited concerns for this species, on the early success of its translocation from tubers as determined through measures of emergence, survival, growth, and reproduction of two cohorts. Our findings suggest that translocation from tubers could be a viable option to assist the conservation of P. integrilabia relative to its propagation from seed, but that low early emergence, survival, and flowering rates should be considered in translocation plans. Our results also indicate that translocation and ongoing habitat management should consider the potential for light availability to differentially impact distinct plant life stages and influence deer herbivory. We recommend that additional translocation studies designed to investigate the influence of site conditions on outcomes could improve the success of such efforts as well as inform the management of extant occurrences.
... Primary pollinators reportedly vary among the species. However, species of swallowtail butterflies (Papilio spp.) have been observed as pollinators or visitors to all five species in the complex (Cole and Firmage 1984, Folsom 1995, Hapeman and Inoue 1997, Robertson and Wyatt 1990, Smith and Snow 1976, Zettler et al. 1996, which can explain hybridization events. Folsom (1995) argues that differences in spur length and column morphology between P. ciliaris, P. chapmanii and P. cristata lead to pollinia being deposited at different parts of the insect (Hapeman and Inoue 1997), thus keeping crosspollinations a rare event and maintaining the integrity of the three taxa. ...
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The orange and white fringed orchids in section Blephariglottis of Platanthera subg. Blephariglottis are among the showiest terrestrial orchids in the US. Still, frequent hybridization between closely related species can make field identification difficult, and differing perceptions of species boundaries challenge a common understanding of which taxa should be considered distinct entities. In order to evaluate species boundaries in the section, we explored quantitative morphological variation within and among taxa by assessing seven floral traits in populations of five species and three putative hybrids across the eastern US from Pennsylvania to Texas. We found that floral traits generally discriminated well among taxa, albeit with some overlap for closely related taxa. Two of the hybrids displayed traits intermediate to those of their parents, whereas the third could not be differentiated from one of its parents. The data revealed considerable intraspecific variation along a north-south gradient for some taxa, which could be related to adaptation to different pollinator faunas across the distribution area. We advocate that descriptions of species, subspecies and varieties should be based on quantitative data across distribution area to cover the breadth of intraspecific variation and avoid artificial splitting due to geographically limited sampling.
... Herbarium codes follow Thiers (2017). Literature for pollinators: 1 Gregg (1991); 2 Mehrhoff (1983); 3 Vitt and Campbell (1997); 4 Boland and Scott (1991); 5 Heinrich (1975); 6 Thien and Marcks (1972); 7 Firmage and Cole (1988); 8 Lehmberg (2002); 9 van der Pijl and Dodson (1966); 10 Stoutamire (1967); 11 Stoutamire (1971); 12 Wright (1975); 13 Barrett and Helenurm (1987); 14 Plowright et al. (1980); 15 Davis (1986); 16 Bender (1985); 17 Catling and Knerer (1980); 18 Nilsson (1981); 19 Case and Bradford (2009); 20 Guignard (1886); 21 Guignard (1887); 22 Vogt (1990); 23 Dieringer (1982); 24 Ackerman (1975); 25 Kipping (1971); 26 Kallunki (1976); 27 Kallunki (1981); 28 Stevenson (1973); 29 Homoya (1993); 30 Smith and Snow (1976); 31 Catling and Catling (1991); 32 Cole and Firmage (1984); 33 Luer (1975); 34 Robertson and Wyatt (1990a); 35 Robertson and Wyatt (1990b); 36 Frame and Gregg (1981); 37 Gregg (1981); 38 Gregg (1983); 39 Gregg (1990); 40 Folsom (1984); 41 Light (1998); 42 Moldenke (1949); 43 Stoutamire (1974); 44 Zettler et al. (1996); 45 Duckett (1983); 46 Little et al. (2005); 47 Bowles (1983); 48 Sheviak and Bowles (1986); 49 Cuthrell (1994); 50 Robertson (1893); 51 Dexter (1913); 52 Stoutamire (1968); 53 Thien (1969); 54 Thien and Utech (1970); 55 Hapeman (1997); 56 Cuthrell and Rider (1993); 57 Sharma et al. (2003); 58 Phillips (2003); 59 Hapeman (1996); 60 Sheviak (1982); 61 ; 62 Catling (1983); 63 Robertson (1929); 64 Ames (1921); 65 Godfrey (1933); 66 Larson and Larson (1987); 67 Larson and Larson (1990); 68 Hogan (1983); 69 Mosquin (1970); 70 Freudenstein (1997); 71 Reeves and Reeves (1984); 72 Whigham and McWethy (1980); 73 Stoutamire (1978); 74 Keenan (1996); 75 Lownes (1920); 76 Medley (1979 20TH CENTURY. Twenty taxa were described during the 20th century, belonging primarily to two categories: (a) cryptic species formerly incorporated under more widespread and polymorphic species and (b) hybrids. ...
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In celebration of the 150th anniversary of the Torrey Botanical Society and in conjunction with the publication of my treatment with John Freudenstein of Orchidaceae for The New Manual, I review the current state of scientific understanding of northeastern North American Orchidaceae. A historical overview of species description is presented; expanded phylogenetic reconstructions are provided for Galearis, Goodyera, and Spiranthes; the systematics and species boundaries of Cypripedium, Platanthera blephariglottis, P. cristata, P. grandiflora, and the Spiranthes cernua species complex are discussed; possible drivers of biodiversity are presented; and a synthesis of known pollinators for northeastern North American orchids is provided. A chronologic analysis of herbarium specimens for boreal-montane orchid species and southern orchid species at their northern distributional limits within New York State indicate broad-scale population collapses and a hollowing out of species diversity. Despite the overall collapse of many orchid populations, I also discuss several species that have recently been added to the state flora or rediscovered after a period of presumed extirpation.
... -The pollination biology of H. macroceratitis was investigated to determine what role an insect pollinator may play in the long-term conservation of the species. Following the methods outlined by Zettler et al. (1996) pollinator observations, nectar volume, and nectar sugar concentrations were conducted on 26-28 August 2004. Given that H. macroceratitis has white to cream colored flowers and produced a scent only at night, it was not surprising that a night-flying moth STEWART & KANE -Orchid Conservation in Florida 00 (Cocytius antaeus, giant sphinx moth) was observed visiting and probing individual flowers. ...
Conference Paper
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Seeds of an endangared orchid, Platanthera integrilabia, were exposed to one of three light treatments: 7 days initial darkness followed by 16 h per day photoperiods, 16 h per day photoperiods for 7 days followed by darkness, and 16 h per day photoperiods. Alternatively, a continuous dark treatment in symbiotic and asymbiotic culture was provided. Seeds exposed to 16 h per day photoperiods or an initial 7 days of darkness followed by 16 h per day photoperiods were largely inhibited from germinating. Seeds exposed to 16 h per day photoperiods during the photoperiods during the first 7 days after fungal inoculations followed by darkness had a significantly higher percent germination than the other treatments, including those in continuous darkness. Seedling (protocorm) development (i.e., formation of leaf primordia) was also enhanced by initial light compared to seedlings under continuous darkness. We speculate that light exposure followed by darkness occurs naturally starting with the shedding of seeds from capsules to their immersion in a substrate where germination occurs. The beneficial effects of light in this study argues in support of light usage to stimulate germination and seedling development of temperate terrestrial orchids.
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