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Marsilea, an amphibian fern genus (containing ca. 80 species) characterized by their unusual leaves and reproductive structures, is distributed over the five continents. To investigate the adaptation traits of three Marsilea species (M. crenata, M. quadrifolia, and M. schelpiana), distributed in different geographic regions, to terrestrial conditions, we compared morphological features, optical properties and photosynthetic performance of leaflets of the three species grown in terrestrial environment. The results showed that leaflets of the three species had significant differences in some of the ecophysiogical traits. Among the three species, M. quadrifolia (distributed in temperate region where receiving low precipitation) had the highest trichome density on its leaflet surface and the highest water use efficiency, M. schelpiana (mainly in southern Africa where accepting high level of solar irradiance) had the tallest petiole and the highest leaf dissection index, total stomatal pore area index, PSII electron transport rate and photosaturated photosynthetic rate, M. crenata (mainly in southeastern Asia region where receiving high precipitation and with high humidity) had the lowest leaf dissection index and water use efficiency. Accordingly, leaf characteristics of the three Marsilea species reflect the climate pattern of their habitats. The results also suggest that water availability and light intensity are two of the important factors contributing to the geographic distribution of the three species. |
