Rhythmic behaviour is quintessential to life itself. Advances in plant molecular biology, micro/nanotechnology and applied mathematics provide new tools for understanding how environmental signals and internal clocks regulate rhythmic gene expression and development, and how these signals are translated into physiological responses at various levels of structural organisation. This book reviews recent progress in assessing underlying mechanisms controlling plant circadian and ultradian oscillations, and their physiological implications for growth, development, and adaptive responses to the environment. It focuses on mechanisms and theoretical concepts at the level of the cell to the entire plant. Written by a diverse group of leading researchers, it will surely spark the interest of readers from many branches of science: from physicists and chemists wishing to learn about multi-faceted rhythms in plant biology, to biologists dealing with state-of-the-art modelling of such rhythmic phenomena.