Dormancy is a resting state that occurs in animals and plants, when growth stops and the internal processes, principally respiration, are slowed down. In animals, dormancy during the winter is termed hibernation, while dormancy in the summer or dry season, such as in the lung fish and earthworm, is termed aestivation (or estivation). In plants, dormancy during adverse conditions is manifest in the lack of growth of perennial plants such as grasses, the loss of foliage by deciduous trees, and the production of underground perennating organs such as bulbs, corms, and tubers.