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 | H. NOSRATI, R. HAJIBOLAND, A. RAZBAN-HAGHIGHI, M. NIKNIAZI Research Article Turk J Bot 35 (2011) 553-560 © TÜBİTAK doi: A comparative assessment of fruit formation in some orchid species from the southern Caucasus region Houshang NOSRATI*, Roghieh HAJIBOLAND, Ahmad RAZBAN-HAGHIGHI, Maryam NIKNIAZI Department of Plant Science, University of Tabriz, Tabriz - IRAN Received: Accepted: 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 < ; and compared to , N = 44, P < , respectively). We located 20 plants of P. bifolia in 2 different locations with an average fruit set of . 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. Key words: Cephalanthera longifolia, Dactylorhiza romana, Ophrys scolopax, Orchis simia, Platanthera bifolia, fruit set Introduction Over 90% of the 250,000 extant angiosperm species are pollinated by animals, primarily insects (Buchmann & Nabhan, 1996). Pollination failure is common in plant .
