Integrated physiological units in plants.

Plants, like animals, have traditionally been viewed by ecologists and evolutionary biologists as fully integrated organisms capable of sharing energy, nutrient and water resources throughout their bodies. Recent studies, however, indicate that many plants may be more realistically considered to be assemblages of semiautonomous integrated physiological units (IPUs)(1), consisting of physiological(2) as well as morphological subunits(3). The existence of IPUs may have important implications for the study of herbivore, frugivore and pollinator interactions with plants, as well as for studies of patterns of resource distribution that require understanding of the environmental regulation of plant development.