Platanthera Praeclara Research Articles

Observation: Leafy spurge control in western prairie fringed orchid habitat

The western prairie fringed orchid (Platanthera praeclara Sheviak and Bowles) is a threatened species of the tallgrass prairie. Invasion by leafy spurge (Euphorbia esula L.) is a serious threat to western prairie fringed orchid habitat. The objectives of this study were to develop a herbicide treatment to control leafy spurge while sustaining western prairie fringed orchid populations and to evaluate the soil seedbank composition of leafy spurge-infested sites to guide long-term management strategies. Quinclorac (3,7-dichloro-8-quinolinecarboxylic acid), imazapic {(+/-)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2=yl]-5-methyl-3-pyridinecarboxylic acid}, and glyphosate [N-(phosphonomethyl)glycine] plus 2,4-D (2,4-dichlorophenoxy acetic acid) were applied in the fall for 2 consecutive years, and changes in leafy spurge cover, density, yield, and herbaceous yield were assessed. In a separate study, quinclorac, imazapic, and glyphosate plus 2,4-D were each fall-applied to 12 western prairie fringed orchids and assessed for reoccurrence and density of orchids 1-year after treatment. Quinclorac and imazapic, but not glyphosate plus 2,4-D, reduced leafy spurge cover, density, and yield without causing deleterious effects to associated native herbaceous cover and yields. Western prairie fringed orchid reoccurrence and density were unaffected by any herbicide 1 year after treatment. Soil cores were removed in spring and fall following the first year herbicide treatment, washed and placed in trays. Seedlings were allowed to germinate for 16 weeks in the greenhouse. Over 50 plant species were identified in the soil seedbank, of which approximately 60% were early seral species indicative of disturbance. Given the dominance of leafy spurge in the seed bank, a long-term management program to control this noxious species is warranted. Although these results are promising, longer-term studies need be conducted to ensure that repeated herbicide treatments do not harm the western prairie fringed orchid.

Symbiotic Seed Germination and Mycorrhizae of Federally Threatened Platanthera praeclara (Orchidaceae)

Abstract In vitro culture of mycotrophic leaf-bearing seedlings of federally threatened Platanthera praeclara Sheviak and Bowles, a terrestrial orchid native to the midwestern prairies, is reported for the first time. Symbiotic germination was evaluated to: (1) determine need for cold moist stratification to enhance seed germination and seedling development and (2) identify the mycobionts that support in vitro germination and development. Germination was improved by exposing seeds to both 4- and 6-mo stratification periods; whereas seeds without stratification failed to germinate in a pilot study. Pretreatment of seeds with 6 mo of stratification combined with inoculation with mycorrhizal fungus derived from a seedling (Ceratorhiza sp., UAMH 9847) supported development of higher stage protocorms and some leaf-bearing seedlings of P. praeclara. Protocorms with developing leaf primordia were also obtained by coinoculation with strains of Epulorhiza and Ceratorhiza. Fungi derived from mature P. praeclara pla...

Quantifying Suitable Habitat of the Threatened Western Prairie Fringed Orchid

Land managers need accurate and quick techniques to identify suitable habitat of species of interest. For species protected by federal or state laws, identification of suitable habitat is critical for developing a conservation strategy that includes reestablishing populations and altering management to address this need. In this research, we quantified vegetative and edaphic habitat of the western prairie fringed orchid (Platanthera praeclara Sheviak and Bowles), a federally listed threatened plant. Lowlands (swales) that supported orchids in our southeastern North Dakota study area were characterized as having a higher soil moisture content within the top 10 cm, when compared to swales devoid of orchids. The vegetative composition of orchid-supporting swales reflected this higher moisture content. These data were then used in developing a logistic regression model to differentiate suitable habitat. The model correctly classified 84% of 38 swales as either orchid-supporting or non-orchid-supporting using 4 variables: percent canopy cover of Baltic rush (Juncus balticus Willd.) and hedge-nettle (Stachys palustris L.), soluble soil magnesium and August surface soil moisture. Land managers can use this model to rapidly assess the suitability of a site in this ecoregion for the orchid. By collecting data on the cover of just Baltic rush, which would take about 45 minutes, and entering it in the equation, a land manager could correctly classify 66% of the orchid swales as either suitable or unsuitable as orchid habitat. This approach, because it incorporates quantitative data and allows managers to rapidly and accurately identify suitable habitats, shows promise for other plant species. DOI:10.2458/azu_jrm_v54i5_wolken

Quantifying suitable habitat of the threatened western prairie fringed orchid

Land managers need accurate and quick techniques to identify suitable habitat of species of interest. For species protected by federal or state laws, identification of suitable habitat is critical for developing a conservation strategy that includes reestablishing populations and altering management to address this need. In this research, we quantified vegetative and edaphic habitat of the western prairie fringed orchid (Platanthera praeclara Sheviak and Bowles), a federally listed threatened plant. Lowlands (swales) that supported orchids in our southeastern North Dakota study area were characterized as having a higher soil moisture content within the top 10 cm, when compared to swales devoid of orchids. The vegetative composition of orchid-supporting swales reflected this higher moisture content. These data were then used in developing a logistic regression model to differentiate suitable habitat. The model correctly classified 84% of 38 swales as either orchid-supporting or non-orchid-supporting using 4 variables: percent canopy cover of Baltic rush (Juncus balticus Willd.) and hedge-nettle (Stachys palustris L.), soluble soil magnesium and August surface soil moisture. Land managers can use this model to rapidly assess the suitability of a site in this ecoregion for the orchid. By collecting data on the cover of just Baltic rush, which would take about 45 minutes, and entering it in the equation, a land manager could correctly classify 66% of the orchid swales as either suitable or unsuitable as orchid habitat. This approach, because it incorporates quantitative data and allows managers to rapidly and accurately identify suitable habitats, shows promise for other plant species.

490 Toward Conserving a Threatened Orchid (Platanthera praeclara)

Platanthera praeclara, commonly called western prairie fringed orchid, is a showy forb native to seven states and one Canadian province. The species had resisted previous attempts at propagation. Small, isolated populations in the sandhills region of western Nebraska are disjunct and visitation by natural pollen vectors appears to be in decline. Modern cultivation practices and other habitat encroachment factors, including urban development, recreational activities, and natural fluctuations in seasonal water availability all have the potential to exert pressure on current populations. Federal and state permits have allowed a limited hand-pollination study to be conducted on federal land. Hand-pollinated plants showed a greater fruit production compared to control plants receiving no human pollination assistance. Germination studies were conducted using aseptic in vitro techniques. The microscopic seeds possess testa that are extremely hard and resistant to liquid absorption, which presents challenges to germination in vitro. These challenges will be discussed. Alternating cold treatments with room temperatures appeared necessary to promote protocorm development after germination. Three media tested produced varying germination responses. Juvenile plants produced through micropropagation can offer propagules for possible future reintroduction efforts of this protected species.

Ceratorhiza pernacatena and Epulorhiza calendulina spp.nov.: mycorrhizal fungi of terrestrial orchids

Two new species of fungi mycorrhizal with terrestrial orchids native to the Canadian prairies are described and illustrated. Ceratorhiza pernacatena sp.nov., from mycorrhizas of Platanthera praeclara, produces globose monilioid cells linked by narrow, tubular, connections that contain the septum between adjacent cells. Hyphae are binucleate, 5–7 μm in width, regularly septate with perforate parenthesomes. Cellulase is produced, but polyphenol oxidase production is low to absent. Epulorhiza calendulina sp.nov., from mycorrhizas of Amerorchis rotundifolia, is distinguished from other Epulorhiza species by the orange to ochre colour of colonies on potato dextrose agar. On corn meal agar, clavate to irregular monilioid cells are produced in short, branched, chains arising from lateral hyphal branches. Runner hyphae are binucleate, 3.0–4.7 μm in width, regularly septate, with flattened, imperforate parenthesomes. Polyphenol oxidase production is lacking, but cellulase is produced. Key words: orchid mycorrhizas, Amerorchis rotundifolia, Platanthera praeclara, Rhizoctonia.

Influence of Environmental Factors and Preliminary Demographic Analyses of a Threatened Orchid, Platanthera praeclara

I n 1987, 160 individual Platanthera praeclara Sheviak and Bowles were permanently marked on 16 transects on the Sheyenne National Grassland, in southeastern North Dakota. They were located on five sites that represented five management regimes: (1) grazed-rotational; (2) grazed-season long (5.5 mo); (3) ungrazed; (4) ungrazed and burned, and (5) grazed and burned. By 1994, only 4% of the originally marked Platanthera praeclara individuals were observed; however, numbers did not differ (P = 0.13) among sites. Beginning in 1990, all Platanthera praeclara individuals in belt transects on each site were marked and counted, and demographic data were recorded. Total orchid density differed (P = 0.04) among sites, but not with a consistent pattern among years (P = 0.001). In some years, Platanthera praeclara density was positively correlated with surface soil moisture. Preliminary demographic analyses indicate that Platanthera praeclara may be short-lived and that absent plants rarely reappear. Cluster analysis indicated that the most common vegetative community supporting Platanthera praeclara was dominated by Poa pratensis L. and Juncus balticus Willd., although Platanthera praeclara density on the Sheyenne National Grassland was most highly correlated with cover of Calamagrostis stricta (Timm.) Koel.