Loutfy Boulos is professor of botany at the National Research Center in Cairo and currently professor of plant taxonomy at the Faculty of Science, Kuwait University. He is the author of Medicinal Plants of North Africa, The Weed Flora of Kuwait, and is co-author with Dr. el-Hadidi of The Street Trees of Egypt (AUC Press, revised edition 1988). M. Nabil El-Hadidi is professor of plant taxonomy and flora of Egypt at the Faculty of Science, Cairo University. He is the editor of Taekholmia, the journal of the Cairo University Herbarium.