Propagation nurseries produce pre-finished plant material (liners), such as ornamental trees, shrubs, and grasses, fruit trees, and annual and perennial flowers. Plants are propagated either by seed or by vegetative means, such as by cuttings, grafting, or tissue culture. Some nurseries specialize in growing and selling pre-finished plants to other growers, making propagation their sole business. However, some wholesale nursery operations have their own propagation areas where plants are produced for in-house use.