A comparative assessment of fruit formation in some orchid species from the southern Caucasus region

Abstract

The distribution and population size of 5 orchid species (Cephalanthera longifolia, Orchis simia, Platanthera bifolia, Dactylorhiza romana, and Ophrys scolopax) were studied in the southern Caucasus based on the individual numbers in a given area. The fruit set was recorded for the latter 3 species and compared in natural and control groups (pollinators prevented) for D. romana and O. scolopax. We compared the obtained fruit set values with those reported from other regions. The distributions of the 5 species were completely fragmented and the population sizes were extremely small. This is the first report of O. scolopax from the region, recorded only in a remote location with a population of about 44 plants. The average fruit sets of D. romana and O. scolopax found in nature were significantly higher than those of the control groups (27% compared to 16%, N = 67, P < 0.001; and 10.4% compared to 3.04%, N = 44, P < 0.02, respectively). We located 20 plants of P. bifolia in 2 different locations with an average fruit set of 62.7%. Only 2 O. simia plants were found in the region. Our data show that pollinators have a significant role in the fruit sets of D. romana and O. scolopax and that the orchids studied require urgent conservation action.