Plants utilize light not only for photosynthesis but also as environmental signals. They are capable of perceiving wavelength, intensity, direction, duration, and other attributes of light to perform appropriate physiological and developmental changes. This volume presents overviews of and the latest findings in many of the interconnected aspects of plant photomorphogenesis, including photoreceptors (phytochromes, cryptochromes, and phototropins), signal transduction, photoperiodism, and circadian rhythms, in 42 chapters. Also included, is a prologue by Prof. Masaki Furuya that gives an overview of the historical background. With contributions from preeminent researchers in specific subjects from around the world, this book will be a valuable source for a range of scientists from undergraduate to professional levels.