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The size of Rhododendron sichotense seeds and exotesta cells from 20 populations were studied using a scanning electron microscope (SEM). The results of a correlation analysis showed that seed size depends on bioclimatic factors. As a species marker, we used the exotesta cell elongation coefficient. This characteristic was unresponsive to environmental variables, demonstrating its taxonomic significance. In the centre of the species range, the samples had an exotesta cell elongation coefficient that was typical for the species, but in samples from the far northern and southern parts of the range, where the distribution of R. sichotense meets that of of R. dauricum L. and R. mucronulatum Turcz., respectively, the value of the exotesta cell elongation coefficient was intermediate between these species. Therefore, the exotesta cell elongation coefficient can be recommended for use in the detection of hybridisation areas. |
