Variability of needle morpho-anatomy of natural pinus heldreichii populations from scardo-pindic mountains

Eight morpho-anatomical properties of two-year-old needles of Pinus heldreichii (Bosnian pine) from the Scardo-Pindic mountain massif in Serbia (Kosovo, Mt. Ošljak) and North Macedonia (Mt. Gali.ica) were investigated. All measured characteristics, except for needle length, were inspected on mid-needle cross-section. Cross-sections were obtained with razorblade, while measurements were performed with Leica-Gallen III light microscope. The mean values of the analyzed characters were as follows: 5.91 cm (needle length), 1.35 mm (needle width), 0.85 mm (needle thickness), 25.05 μm (cuticle + epidermis thickness), 69.90 μm (height of hypodermal cells), 21.76 μm (resin duct diameter), 3.4 (number of hypodermis layers), and 3.6 (number of resin ducts). P. heldreichii needles also had 2-5 hypodermis layers and 0-12 resin ducts. The highest variation was in the number of resin ducts (CV=27%). In comparison with previously investigated needles from the Dinaric mountains, P. heldreichii needles from the Scardo-Pindic massif were shorter and had a thicker layer of hypodermis. PCA and CA visualize partial segregation of P. heldreichii populations between the two mountain massifs