The plan for this book dates back to 1935. At that time, I realized that my way of presenting the subjects of botany had its advantages compared to the methods commonly used. In particular, it became urgently necessary to incorporate a coherent theory of reproduction and inheritance into the framework of general botany. The reason this did not happen was that no books of mine could be published during the Third Reich. After the collapse, the catastrophe had to be painstakingly overcome, and the time available to dedicate to scientific matters was limited. Thus, it has become late, and other botany textbooks have been published before mine. Hopefully, it is not too late. I have made an effort to outline the thought processes that I have been using in my teaching for over 25 years. I owe my thanks to many helpers.