The aim of the present study was to understand the ecological adaptation of Pinus roxburghii Sarg. in the North-West Himalayan region. P. roxburghii needles showed morphological, epidermal, and anatomical variation at different altitudes. | Turkish Journal of Botany Research Article Turk J Bot (2013) 37: 65-73 © TÜBİTAK doi: Comparative morphological, epidermal, and anatomical studies of Pinus roxburghii needles at different altitudes in the North-West Indian Himalayas Satyendra Prakash TIWARI*, Pradeep KUMAR, Deepika YADAV, Devendra Kumar CHAUHAN Sahni Palaeobotany Laboratory, Department of Botany, University of Allahabad, Allahabad, India Received: Accepted: Published Online: Printed: Abstract: The aim of the present study was to understand the ecological adaptation of Pinus roxburghii Sarg. in the North-West Himalayan region. P. roxburghii needles showed morphological, epidermal, and anatomical variation at different altitudes. Needle length was negatively correlated with altitude. Stomatal characters like stomatal density, stomatal index, and guard cell lengths were found to be affected by environmental factors and showed a direct correlation with altitude. The results showed that potential conductance index was dependent on the climatic conditions of the habitat. The anatomical properties of needles exhibited variation from lower to higher elevation, especially in the number and position of resin ducts. Key words: Ecological adaptation, Pinus, resin duct, stomatal density, stomatal index 1. Introduction Chir pine (Pinus roxburghii Sarg.) is the dominant tree species in the North-West region of the Indian Himalayas. It is a hard pine of lower elevation, occurring between altitudes of 500 and 2500 m and is extensively distributed from Bhutan to Afghanistan. Chir pine grows gregariously, often forming pure formation in xerophytic and well-lit environments (Mehra, 1988). P. roxburghii is an economically valuable species, balancing the ecosystem of the Indian mountains. The plants show microhabitat-related morphological and anatomical features at different altitudes. Körner (2007) proposed the
