Providing basic information on reactive oxygen species (ROS), this volume describes new developments in the action of ROS, the role of antioxidants, and the mechanisms developed to scavenge free radical associated cellular damage. It illustrates the chemistry of ROS, ROS signaling, antioxidative defense systems, transgene approaches in scavenging ROS, and the role of oxidative stress in plant recalcitrance and hyperhydricity as well as how plants orchestrate their response to morphogenesis. It also includes a brief account of the use of medicinal plants for natural antioxidants, emphasizing biochemical details.