Foliar Structure of Several Species of Epiphytic Tillandsia(Bromeliaceae)

We analyzed and compared external and internal structure of the leaves of three epiphytic Tillandsia species(Tillandsia stricta 'Hard leaf',T.stricta 'Cotton candy' and T.filifolia) and one terrestrial species of Bromeliaceae,Guzmania 'Denise',by scanning electron microscope(SEM) and paraffin section.The results showed that the sunflower-shaped trichomes covered the leaf surface in all species studied.The foliar trichomes were made up of disc cells,ring cells and wing cells,and the central disc cells were connected with mesophyll cells by a passage with 2-3 cells.The foliar trichomes of the epiphytic Tillandsia were white and waxy with high densities,but stomata is little or not detectable,which indicated the foliar trichomes would functioned as reduction of transpiration,water repellency and photoprotection other than water and nutrient Absorption.In addition,the foliar trichomes among different epiphytic Tillandsia species were different in density,shape and size,which suggested that different species have been adapted to their ancestral and present environment.