I have been teaching series of undergraduate courses in agriculture and natural resources in three Universities in Ethiopia namely; Mizan Tepi, Debre Markos and Jimma Universities for the past 8 years. In the process, I have closely interacted with students of varied backgrounds and taken note of their problems. In most cases, students are keen to learn all subjects offered in a semester but they find it difficult to cope-up with lecture notes, assignments, term papers and consultation with given reference books, journals or periodicals. Plant physiology is a required course for agriculture and biology students at undergraduate and graduate levels all over the world. Considering the need for a concise text book, I embarked upon preparing this teaching material on plant physiology covering all topics of importance. I still feel that this write-up is not a substitute for standard text books but will be useful to undergraduate and graduate students. I also recognize the fact that emphasis on individual topics varies with instructors and hence suggestions for the improvement would highly be appreciated and welcome.