POLYMORPHISM AND DEVELOPMENT OF POSIDONIA-OCEANICA TRANSPLANTED FROM DIFFERENT PARTS OF THE MEDITERRANEAN INTO THE NATIONAL-PARK OF PORT-CROS

A collection of Posidonia oceanica (L.) Delile has been constituted in the National Park of Port-Cros, France, from 278 cuttings and seedlin gs originating from 12 populations in different parts of the Mediterra nean in Algeria, France, Greece, Italy, Spain and Turkey. In all plant s of this collection, change in leaf width and in the number of apices , has been followed every year in autumn, from initial transplanting i n 1989 to 1991. At the time of transplanting, the inter-origin mean le af width was 8.57 mm, with a difference of 4.81 mm between the means f rom different origins. Differences in leaf width were significant betw een 5 batches from different places. After two years' growth at Port-C ros, the differences diminished by nearly half and only the cuttings f rom Algeria (widest leaves) and Corsica-Piantarella (narrowest) remain significantly different from the other batches. This indicates a prog ressive reduction in the influence of the original environment on mate rial transplanted into the same site. Variation still remains between batches in the number of apices per plant formed over two years, but f urther observations are necessary to show whether these differences wi ll be retained.