A cultivar is a plant or group of plants selected for desirable characteristics that can be maintained by propagation. Most cultivars have arisen in cultivation but a few are special selections from the wild. Popular ornamental garden plants like roses, camellias, daffodils, rhododendrons and azaleas are cultivars produced by careful breeding and selection for flower colour and form. Similarly the world's agricultural food crops are almost exclusively cultivars that have been selected for characters like improved yield, flavor, and resistance to disease: very few wild plants are now used as food sources. Trees used in forestry are also special selections grown for their enhanced quality and yield of timber.Cultivars form a major part of Liberty Hyde Bailey's broader grouping, the cultigen, defined as a plant whose origin or selection is primarily due to intentional human activity. Cultivar was coined by Liberty Hyde Bailey and it is generally regarded as a portmanteau of "cultivated" and "variety", but could also be derived from "cultigen" and "variety".