Cold adaptation drives variability in needle structure and anatomy in Pinus sylvestris L. along a 1,900 km temperate-boreal transect
Occupancy of cold habitats by evergreen species requires structural modification of photosynthetic organs for stress resistance and longevity. Such modifications have been described at interspecific level, while intraspecific variation has been underexplored. To identify structural and anatomical traits that may be adaptive in cold environments, we studied intraspecific variability of needles of S