The effects of inflorescence size and flower position on female reproductive success in three deceptive orchids

摘要

Most Mediterranean orchids are deceptive, offering no reward to insect pollinators. In the absence of a reward, inflorescence size and flower position within inflorescence may be associated with the timing and the numbers of pollinators attracted, thus influencing the final reproductive success. Pollination biology and breeding system were investigated in three deceptive orchids, Orchis italica, O. anthropophora, and Anacamptis papilionacea. Although all examined orchids were self-compatible, bagged inflorescences produced no fruits. Artificial pollination resulted in a 76-79% fruit set by induced autogamy, a 70-76% one by geitonogamous pollination, and a 79-87% one by allogamous pollination. The natural fruit set in the open-pollinated control was 14-16%. Fruit production was neither related to the inflorescence size, nor to the number and position of flowers within the flowering spike, suggesting that variation in these floral traits does not influence pollinator attraction or female reproductive success.