Effect of tree age on needle morphology and anatomy of Pinus uliginosa and Pinus silvestris – species-specific character separation during ontogenesis

Differences in morphological and anatomical characters of needles between seedlings, saplings and adult trees of the endangered Pinus uliginosa from the Węgliniec Nature Reserve in SW Poland were examined biometrically and statistically assessed using the Student's t-test, Tukey–Kramer test, step-wise discrimination and agglomeration on Euclidean distances according to Ward's method. Pinus sylvestris adults and seedlings were used as comparative material. The results show that needles of all three P. uliginosa generations differ significantly from each other. In seedling needles, several anatomical characters were similar to those of P. sylvestris growing in the vicinity of the reserve. However, P. uliginosa had a lower number of resin canals, lower frequency of fibre-like sclerenchyma cells and higher frequency of thin-walled sclerenchyma cells with large lumens in the spaces between vascular bundles. Needle characters of saplings and adult trees of both species were distinctly more different than it was the case in the seedling stage.