Morpho-anatomical variation and their phylogenetic implications in native and exotic species of Pinus L. growing in the Indian Himalayas

ABSTRACT Pine is native to all continents and some oceanic islands of the northern hemisphere, chiefly in boreal, temperate or mountainous tropical regions; reaching its southernmost distribution below the equator in Southeast Asia. Pinus is divided into two subgenera, Strobus, and Pinus by the number of vascular bundles present in the needles. Comprehensive and detailed anatomy of needles in ten species of Pinus using nine anatomical traits was carried out. These morphological and anatomical traits supported the classification of the genus up to section level. It was observed that number of needles per fascicle varied along with other related traits such as thickness and width of vascular bundles, the diameter of resin ducts, the thickness of epidermis and thickness and width of endodermal cells that show remarkable variations among different species selected for the present study. The data can be used as a tool for identification and classification of Pinus upto genus and species level. We also found that similarity and differences in leaf anatomical traits supported the molecular phylogeny of Pinus conducted by several researchers.