A generation is "all of the people born and living at about the same time, regarded collectively." It can also be described as, "the average period, generally considered to be about 20–⁠30 years, during which children are born and grow up, become adults, and begin to have children." In kinship terminology, it is a structural term designating the parent-child relationship. It is known as biogenesis, reproduction, or procreation in the biological sciences. Generation is also often used synonymously with cohort in social science; under this formulation it means "people within a delineated population who experience the same significant events within a given period of time". Generations in this sense of birth cohort, also known as "social generations", are widely used in popular culture, and have been the basis for sociological analysis. Serious analysis of generations began in the nineteenth century, emerging from an increasing awareness of the possibility of permanent social change and the idea of youthful rebellion against the established social order. Some analysts believe that a generation is one of the fundamental social categories in a society, while others view its importance as being overshadowed by other factors including class, gender, race, and education, among others.

Rosaceae, the rose family, is a medium-sized family of flowering plants, including 4,828 known species in 91 genera. The name is derived from the type genus Rosa. Among the most species-rich genera are Alchemilla (270), Sorbus (260), Crataegus (260), Cotoneaster (260), Rubus (250), and Prunus (200) which contains the plums, cherries, peaches, apricots, and almonds. However, all of these numbers should be seen as estimates – much taxonomic work remains. The family Rosaceae includes herbs, shrubs, and trees. Most species are deciduous, but some are evergreen. They have a worldwide range, but are most diverse in the Northern Hemisphere. Many economically important products come from the Rosaceae. It includes many edible fruits, such as apples, pears, quinces, apricots, plums, cherries, peaches, raspberries, loquats, strawberries, rose hips, hawthorns and almonds. It also includes popular ornamental trees and shrubs, such as roses, meadowsweets, photinias, firethorns, and rowans.