Since higher plants are unable to move in their environment, interesting and mysterious developmental events (allelopathy, phototropism, apical dominance, nyctinasty, flowering, senescence) are observed in their life cycle. Chemical compounds released from plant organs to the neighboring environment stimulate or suppress the development and/or growth of other plants; this chemical interaction is called "allelopathy." The bending of the organs of a plant toward the light is a well-known phenomenon called "phototropism." The growth of lateral buds of some plants is normally repressed by a strongly growing main shoot apex and is the so-called "apical dominance". Plants open their leaves during the day and close them at night as if sleeping is known as "nyctinasty." Herein, recent studies on isolation and structure elucidation of bioactive compounds involved in their life cycle and determination of the molecular mechanisms for these developmental events are described.