| Author(s) | Hussain A. Abulfatih |
| Affiliation | University of Qatar, Faculty of Science, Department of Biological Sciences, P. O. Box: 11828, Doha, Qatar e-mail: abulfatih44@hotmail.com |
| Title | Ecological Anatomy of Xerophytic Leaves from Qatar |
| Source | Journal of King Saud University. Science. Volume 16, No 1. (2004/1424) |
| Abstract | Leaf anatomy of 11 of the most common xerophytic species found in Qatar were investigated, including: Acacia ehrenbergiana, Calotropis procera, Cyperus conglomeratus, Fagonia ovalifolia, Glossonema edule, Heliotropium bacciferum, Lycium shawii, Ochradenus baccatus, Sporobolus arabicus, Tamarix rosmarinus and Ziziphus nummularia. Under the extreme arid conditions leaf anatomy revealed the following features: most investigated species have flattened leaves, coated with a layer of cuticle and one row of epidermal cells. Guard cells are present commonly at the level of the epidermal layer or slightly depressed. Monocot species maintain bulliform cells (motor cells) which play a major role in folding and unfolding of the leaf corresponding with the changes in the environmental conditions, as in Sporobolus arabicus. Trichomes were present with different proportions in different species, as shown in Glossonema edule, Heliotropium bacciferum, Lycium shawii, Sporobolus arabicus, and Ziziphus nummularia. Calotropis procera had a high density of scales on the leaf surface. Palisade tissue is well developed, and characterized by having many layers of elongated cells, rich with chloroplasts. Intercellular spaces are limited in the palisade and spongy tissues. Spongy tissues occupy much less volume if compared with mesophytes and hydrophytes. Vascular bundles usually distributed across the width of the leaf. Vascular bundles are surrounded by a bundle sheath of parenchyma cells in the case of Sporobolus arabicus. Such bundle sheath is known to play an important role in the process of photosynthesis under extreme arid conditions. Leaves in many instances maintained strengthening tissues (fibers), especially in Sporobolus arabicus. |
