Although there is no one set of "official" classification system of roses, there are many different popular rose classification schemes that are employed throughout the world. The most popular of the systems in use has been proposed by The American Rose Society in cooperation with the World Federation of Roses. Although this classification system is not the only one in use, a large majority of internationally established societies have adopted this scheme for classifying roses.
According to the American Rose Society, there are three main groupings of roses: the Species; Old Garden Roses; and Modern Roses. Species Roses, the origin of every other rose class, are commonly referred to as "wild roses." These "wild roses" are easy to identify, as they normally have five petals, are once-blooming, and are generally thorny shrubs or climbers. Several popular Species Roses include: Cherokee Roses, Dog Roses, Gallic Roses, French Roses, and Redleaf Roses. Species Roses can be found throughout the Northern Hemisphere, as they flourish in temperate climates.
Unlike Species Roses, which existed millions of years before man walked the earth, Old Garden Roses are identified as a major class of roses recognized before 1867.
Most Old Garden Roses bloom once per season, usually at the arrival of summer. Old Garden Roses occur in a variety of shrub and vine sizes. Although colors vary, Old Garden Roses are typically white or pastel in color. These "antique roses" are generally preferred for lawns and home gardening because they are easy to care for. Several groupings of roses are classified as Old Garden Roses including: China, Tea, Moss, Damask, Bourbon, Hybrid Perpetual and Noisette roses. Many "antique roses" have a strong sweet scent, which makes them very desirable.
Old Garden Roses are the predecessors of Modern Roses. Any rose which has been identified post 1867 is considered a Modern Rose. This group of roses are very popular. The Modern Rose is the result of cross breeding the hybrid tea with the polyanthus. The colors of a Modern Rose are lovely, rich and vibrant. Most of the roses found in this class flower repeatedly when cared for properly. Perhaps that is why horticulturists find this class so attractive. The most popular roses found in the class of Modern Roses are the hybrid tea, floribunda, and grandiflora. Although Modern Roses are adored by florists and gardeners, they do not adapt well to colder environments.
After a rose has been classified according to the three main groupings, a rose can then be further classified by color, scent, growth habit, ancestry, date of introduction, blooming characteristics and size. It is very difficult for horticulturists to classify every rose, especially the hybrid roses which often seem like a grouping of their own. While there has been much debate on classifying roses, the American Rose Society appears to have the most functional system for these stages of classification. Perhaps this is why the American Rose Society's classification system has been adopted by so many rosarians the world over.