Morphological variability of Carex spicata Huds. utricles among plant communities

Differentiation in the size and number of seeds among populations or particular individuals of a given species may depend on genetic features and environmental conditions. The objective of our study was to answer two questions: whether any differences exist in the size and shape of utricles among Carex spicata populations growing in several plant communities and whether the hypothesized differences remain constant in ‘common garden’ conditions (i.e. if the sedges grown in different plant communities are evolving distinctly separate ecotypes). We studied utricle morphological traits (projected area, width, length, W/L ratio and projected perimeter) and number of utricles per spike collected from plants grown in five different plant communities (natural sites) and from plants transferred to common garden conditions. C. spicata utricles showed significant variability of morphological traits that depended on the plant community of origin. Among five plant communities, the largest utricles were found in Agropyron repens–Urtica dioica and Convolvulo arvensis–Agropyretum repentis communities, while the smallest ones were in plants from the Lolio-Plantaginetum community. The similarity of the analyzed populations regarding sedge utricle traits corresponded to the similarity of plant communities where the populations had grown. Moreover, the differences in utricle traits collected from natural conditions remained stable in common garden conditions. This indicated that differences in traits among utricles had a physiological dependence on different biotope conditions or different interspecific interactions prevailing in the particular plant communities. The relationship between the similarities in the diaspores of the populations studied and the similarities in the ecological conditions of the communities may also indicate that the variability of utricles is important for evolution and adaptation.The results support the hypothesis that C. spicata populations in different communities are producing separate ecotypes, i.e. specific species forms with genetically fixed traits adapted to narrowly determined habitat conditions.