Proceedings 5th International Conference on the Ecology of Invasive Alien Plants 13-16 October 1999 - La Maddalena - Sardinia - Italy ORCHIDS AS INVASIVE PLANTS Wojciech Adamowski Bialowieza Geobotanical Station, Warsaw University Ul. Sportowa 19 17-230 Bialowieza Poland Tel +48 85 68 12 548, Fax +48 85 68 12 479
[email protected] Extinction or endangerment of many orchid species is well known fact. However, also in this group one can find invasive species. The paper include list of more than twenty taxons, spreading in new countries and even invading natural plant communities. European Epipactis helleborine occurs in a variety of anthropogenic habitats and broad- leaved forests in Eastern part of Northern America. In western Europe, on pine and spruce plantations, boreal orchids Goodyera repens and Listera cordata are spreading. In tropical zone most successful invaders are African species: Oeceoclades maculata in Southern and Central America and Monadenia bracteata in Western and Southern Australia. Some orchids, commonly cultivated, escape in two geographical regions, e.g. Epidendrum o'brienianum in Eastern Australia and Hawaii Islands. Most rich in naturalised orchids are Central America and Hawaii Islands. Common characters of many invading orchids are: - quick development (Oeceoclades maculata 1 year from seed to flower in favourable conditions!) - autogamy - apomixis - wide ecological amplitudes - broad natural distribution In most cases, intentional human activity (cultivation) was very important factor for further successful spreading. Unintentional activity (transformation of habitats, accidental introductions) seems to be of similar importance. This phenomenon can be more common, particularly in tropical countries, where orchid flora is rich, and conditions for cultivation more favourable.