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The objective of this study was to investigate the ranges of intra- and interindividual variability on the example of R. canina. For this purpose, four flowers were collected randomly (72 flowers in total)from 18 wild shrubs of R. canina growing in one population in Poznań (Poland)and then, from each flower, 50 correctly formed pollen grains (200 pollen grains per each individual)were selected. Inter- and intraindividual pollen grain variability was characterised based on 3600 pollen grains. They were analysed for seven quantitative features, i.e. length of polar axis (P), equatorial diameter (E), thickness of the exine along the polar axis (Exp), length of ectocolpi (Le) and P/E, Exp/P, and Le/P ratios. Our study revealed highly significant differences among flowers of the particular R. canina individuals with respect to all pollen grain biometrical features. In addition, it showed that the assessment of the full range of variability in pollen grain biometric features within one individual (shrub)was more reliable if we examined several pollen grains from several flowers than for the same number of pollen grains derived from a single flower. We also found statistically significant differences among particular individuals in all pollen grain features. This proves that in order to well characterise a population of a given species from the point of view of palynology, the plant material should derive from a possibly numerous number of individuals (shrubs).
The variability of pollen grains of 16 species from genus Rosa L. was studied (i.e. Rosa agrestis, R. canina, R. dumalis, R. gallica, R. inodora, R. jundzillii, R. kostrakiewiczii, R. majalis, R. micrantha, R. mollis, R. pendulina, R. rubiginosa, R. sherardii, R. tomentosa, R. villosa, and R. zalana). The material came from 107 native localities of those species in Poland. The measurements are based on at least 30–50 randomly selected mature pollen grains per specimen. In total, 3510 pollen grains were examined. They were analysed for 8 quantitative features, i.e. length of polar axis (P), length of equatorial axis (E), exine thickness on the pole (Exp), exine thickness at the equator plane (Exe), length of ectocolpi (Le), P/E ratio, and relative thickness of exine (Exp/P and Exe/E ratio). Statistically significant differences were found among the examined species with regard to all analysed pollen features. The pollen and ectocolpi dimensions (P, E and Le) were largest in R.gallica (35.9, 28.1, and 28.0 μm, respectively) and smallest in R. majalis (27.0, 20.2, and 21.2 μm, respectively). The mean coefficients of variability of the pollen features measured can be used to arrange the examined rose species from the least to the most variable as follows: R. pendulina, R. villosa, R. jundzillii, R. inodora, R. canina, R. rubiginosa, R. dumalis, R. gallica, R. agrestis , R. micrantha, R. zalana, R. tomentosa, R. sherardii, R. majalis, R. kostrakiewiczii and R. mollis. The obtained data failed to confirm fully both the division of the Rosa genus currently in force in taxonomy into sections as well as relationships among the examined species from the Caninae section. In addition, values of morphological characters of the same species may differ considerably from one another. The extent of these differences indicated that it was necessary to measure large numbers of pollen grains in order to obtain accurate biometric data.
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