Generally, the term deciduous means "the dropping of a part that is no longer needed" and the "falling away after its purpose is finished". In plants, it is the result of natural processes. "Deciduous" has a similar meaning when referring to animal parts, such as deciduous antlers in deer, deciduous teeth (baby teeth) in some mammals (including humans); or decidua, the uterine lining that sheds off after birth.
Wood from deciduous trees is used in a variety of ways in several industries including lumber for furniture, construction and flooring (oak), ornamental, bowling pins and baseball bats (maple) and furniture, cabinets, plywood and paneling (birch).
In botany and horticulture, deciduous plants, including trees, shrubs and herbaceous perennials, are those that lose all of their leaves for part of the year. This process is called abscission. In some cases leaf loss coincides with winter—namely in temperate or polar climates. In other parts of the world, including tropical, subtropical, and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall.
The converse of deciduous is evergreen, where foliage is shed on a different schedule from deciduous trees, therefore appearing to remain green year round. Plants that are intermediate may be called semi-deciduous; they lose old foliage as new growth begins. Other plants are semi-evergreen and lose their leaves before the next growing season, retaining some during winter or dry periods. Some trees, including a few species of oak, have desiccated leaves that remain on the tree through winter; these dry persistent leaves are called marcescent leaves and are dropped in the spring as new growth begins.
Many deciduous plants flower during the period when they are leafless, as this increases the effectiveness of pollination. The absence of leaves improves wind transmission of pollen for wind-pollinated plants and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost or, in dry season regions, result in water stress on the plant. Nevertheless, there is much less branch and trunk breakage from glaze ice storms when leafless, and plants can reduce water loss due to the reduction in availability of liquid water during cold winter days.