Taxonomic and geographic differentiation of <i>Pinus mugo</i> complex on the needle characteristics

The phenotypic differentiation of <i>Pinus mugo</i> complex was verified using 31 populations of <i>P. mugo sensu stricto</i>, 11 of <i>P. uncinata</i>, five of <i>P. uliginosa</i>, one of the potential hybrids <i>P. uliginosa</i> × <i>P. mugo</i> and three of <i>P. sylvestris</i>, the latter as a control. The 22 morphological and anatomical needle characteristics were measured and statistically examined to describe the taxa and the population within the taxa differentiation. All the taxa of the <i>P. mugo</i> complex differed significantly from <i>P. sylvestris</i> in most of the verified needle characteristics. Within <i>P. mugo</i> complex, populations of <i>P. uncinata</i> were clearly distinguished from <i>P. mugo s. s</i>. The population of potential hybrid origin was the most similar to <i>P. uliginosa</i>. Populations of the latter taxon were strongly differentiated; some of them were closer to <i>P. uncinata</i>, and others to <i>P. mugo s. s</i>. Within the whole sampled data, three geographic groups of populations were detected: the first included <i>P. uncinata</i> and two of <i>P. uliginosa</i>, the second contained East and South Carpathian <i>P. mugo s. s</i>. with the presumed hybrid population, and the third contained all the other populations of <i>P. mugo s. s</i>. and <i>P. uliginosa</i>. Within <i>P. mugo s. s</i>., the Sudetan populations formed a separate group. <i>Pinus uncinata</i> from the Pyrenees reflected a high level of differentiation. The marginal populations of this taxon (Cebollera, Gúdar, Massif Central) also differed from those in the Pyrenees. The phenotypic differentiation of taxa and populations appeared similar to that which was detected based on <i>cp</i>DNA markers.