Many plants cannot be propagated by leaves alone. One option is to take leaf-bud cuttings. Leaf-bud cuttings are composed of the leaf blade, the petiole, a bud at the base of the petiole, and a portion of the stem. The leaf provides the energy for the development of roots. The roots sprout from the stem and are often concentrated at the node of the stem. The bud develops into the stem of the new plant.
A method of asexual reproduction common with woody plants is grafting. Grafting is the process in which the stem of one plant is made to grow on the roots of another plant. The portion of the graft that is to become the stem is the scion. The lower portion of the plant that includes the root system is called the rootstock or the understock. Budding is a form of grafting in which the scion consists of a bud.
Roses are grafted. Usually, a vigorous, cold-tolerant species of rose is selected for the rootstock. Vigorous rootstocks provide an abundance of water and minerals to the scion. A desired rose hybrid that might not have a strong root system is grafted to the rootstock.
Grafting may involve placing individual buds into a stem or a stem being placed onto another stem. In either case, it is important that the cambium wood of both the scion and the rootstock line up. Once placed together, the union should be protected from moisture loss. Also, the scion and the rootstock materials must be capable of growing together for a successful graft.
Layering is a method of asexual reproduction whereby roots form on a stem while the stem is still attached to the parent plant. The advantage to layering is the parent plant provides the plant-to-be with water and minerals until it produces its own roots. This method is slow as compared to other methods. A form of layering called air layering is used with foliage plants including Dieffenbachia, Ficus, and Dracaena.
Separation and Divison
Propagation of floriculture crops can be done by separating or dividing. This is a common method used with perennials and foliage plants. Some plants produce vegetative plant structures that can be removed intact from the parent plant. Removal and planting of these vegetative structures is separation. With division, the plant roots or the entire plant may be cut into sections to make two or more plants from the original plant. Daylilies can be divided by digging a plant and cutting it into smaller pordons.
There are several methods used to propagate bulbs. Some species of lilies produce bulbils or tiny above-ground bulbs in the axils of their leaves. These can be removed and planted Lilies also may produce tiny
bulbs below the ground called bulblets. Some lilies and fritillaries can be
Tulips and Narcissus reproduce by natural division. Bulbs are produced off the main bulb. These are separated and planted. Hyacinths are very slow to reproduce by natural division. They can be encouraged to produce bulblets by scooping or scoring. Scooping involves the removal of the basal plate of the bulb and the base of all of the bulb scales. Placed upside down in a warm dry cabinet, a bulblet will form at the base of each scale. Scoring is similar to scooping. However, the basal plate is not removed. Two cuts that cross the basal plate are made about a 1/4 inch deep.
Corms, including crocus and gladiola, can be cut into smaller pieces. Each piece of the corm must have a bud that is capable of developing into the stem. Corms also develop small corms called cormels. These miniature corms can be separated and planted.
A very technical method of asexual propagation is tissue culture. Tissue culture involves the culture or growing of small pieces of plant tissue. It is performed on an artificial medium under sterile conditions. Foliage plants, pot plants and cut flowers are propagated by tissue culture methods.