COMPARATIVE ANATOMY OF LEAF LAMINA OF TWENTY SIX WOODY SPECIES OF TAMAULIPAN THORNSCRUB FROM NORTHEASTERN MEXICO AND ITS SIGNIFICANCE IN TAXONOMIC DELIMITATION AND ADAPTATION OF THE SPECIES TO XERIC ENVIRONMENTS

The present study was undertaken to determine the variability in leaf anatomical traits and its relation to taxonomic delimitation and adaptation of the woody species in xeric environments. The results show large variability in anatomical traits with respect to cuticle thickness, presence and absence of trichomes, length of palisade cells and thickness of spongy tissue. Species have been classified on the basis of the length and compactness of palisade cells to determine its relation to the taxonomic delimitation and the adaptation of the species to drought condition. The species viz., Karwinskia humboldtiana, Lantana macropoda, Prosopis laevigata, Zanthoxylum fagara, Helietta parvifolia, Acacia berlandieri and Acacia wrightii having long and compact palisade cells are expected to be efficient in photosynthetic function and adaptation to drought. Future research needs to be directed in this direction.