2). These were the greater yellow lady’s slipper (Cypripedium parviflorum var. pubescens), lesser round-leaved orchid (Platanthera orbiculata) and Spiranthes ochroleuca. The number of sites for P. orbiculata and S. ochroleuca (9 and 4, respectively), years of survey (26 and 24), and initial number of individuals (59 and 41) are very similar. The loss of C. parviflorum var. pubescens is more striking as over 28 years there were more sites (17) and a larger number of individuals

(127). Species with >90 % decline Seven species showed a total decline of >90 % (Table 1; Fig. 2). Among these ALK inhibitor species is the only non-native species of orchid known in the Catoctin Mountains, broadleaf helleborine (Epipactis helleborine). The six other species are Adam and Eve orchid (Aplectrum hyemale), summer coralroot (Corallorhiza maculata var. maculata), autumn coralroot (Corallorhiza

odontorhiza var. odontorhiza), Liparis liliifolia, northern slender lady’s tresses (Spiranthes lacera var. gracilis), and the crippled crainfly Selleckchem GW 572016 (Tipularia discolor). Liparis liliifolia showed an increase in 2008 (Fig. 2). After averaging only 4 plants/year census from 2002 to 2007, 27 plants were found in 2008. Of these species the decline of C. odontorhiza is the most striking with a census high of 977 individuals in 1986 declining to just 70 individuals in 2008. The R2 values for these species are among the highest documented during the study, all of which range from 0.85 to 0.94 (Fig. 2). Species with a <90 % decline Nine species showed declines of <90 % (Table 1; Fig. 3). These species are Coeloglossum viride var. virescens, Clomifene moccasin flower (Cypripedium acaule), showy orchid (Galearis spectabilis), downy rattlesnake plantain (Goodyera pubescens), large whorled pogonia (Isotria verticillata), small green wood orchid (Platanthera clavellata), Platanthera grandiflora, green fringed orchid (Platanthera

lacera), and nodding lady’s tresses (Spiranthes cernua). Cypripedium acaule and G. spectabilis are arguably the most common terrestrial orchids in the Catoctin Mountains. These showed declines from 1,168 and 1,319 individuals to 128 and 66 individuals, respectively. Five of these species (C. viride var. virescens, I. verticillata, P. clavellata, P. grandiflora, and P. lacera) showed an obvious yet unexpected census increase in 2008 (Fig. 3). The R2 values for these species are more variable than the >90 % group. Goodyera pubescens shows the highest R2 value (0.97) of all species in this study. Only P. grandiflora (R2 = 0.53) and C. viride var. virescens (R2 = 0.75) have R2 values <0.85. Species that did not decline Two species did not show declines. These are Platanthera ciliaris and Platanthera flava var. herbiola. Platanthera flava var. herbiola shows a very slight decline (16 plants) but no highly correlated R2 values (Table 1; Fig. 3).