Seed Morphology and Dispersibility of Orchids in Warm Temperate Japan

抄録

Flowering and dispersal phenology, characteristics of fruits, seed shape, and seed and embryo sizes were studied in orchids in the warm temperate zone of Japan. Anemochorous potential was estimated based on the ratio of seed length to embryo length. The data obtained were compared among different life forms: epiphyte, saprophyte (myco-heterotroph), summer green terrestrial and evergreen terrestrial or- chids. The epiphytes, which had the smallest seeds, had the poorest dispersibility. On the other hand, the saprophytes, which had elongated seeds, had excellent dispersibility. Seed size and dispersibility of ter- restrial orchids ranged between those of epiphytes and saprophytes. Most epiphytes had hygroscopic trichomes, which contributed to the release of the seeds from capsule. It was clarified that seed morphol- ogy and dispersal mechanisms in orchids were closely related to their life form.