The book addresses the compelling demand for quantitative training in plant biology, including comparisons of the rate of processes, the size of structures and interactions among different processes, approached at different levels from molecules to the environment. Attention is paid to aspects of modern molecular biology and to modern biophysical treatments of classical transport and circulatory problems. This will allow the reader to become familiar with calculus as a tool to understand plant science. The book discusses specific problems covering six specific topics, and includes an additional section devoted to miscellaneous issues. It is also complemented by appendices describing units, conversion factors, formulae and data relevant to plant biology and to the relationship of plants with the environment.