Dermal tissue covers and protects the plant, and controls gas exchange and water absorption (in roots). Dermal tissue of the stems and leaves is covered by a waxy cuticle that prevents evaporative water loss.

Complex Tissues. Tissues composed of more than one cell type are generically referred to as complex tissues. Xylem and phloem are the two most important complex tissues in a plant, as their primary functions include the transport of water, ions, and soluble food substances throughout the plant.

storage

Epidermis, in botany, outermost, protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant. The epidermis and its waxy cuticle provide a protective barrier against mechanical injury, water loss, and infection.

Air layering can be used to propagate large, overgrown house plants such as rubber plant, croton, or dieffenbachia that have lost most of their lower leaves. Woody ornamentals such as azalea, camellia, magnolia, oleander, and holly can also be propagated by air layering.

Make a 1½-inch wound to start the air layering process. Wrap the wound with sphagnum moss or soil, and cover it with plastic wrap. After placing the soil and plastic wrap around the wound, tie a rubber band at each end to form an airtight seal. Sphagnum moss (or potting soil in a pinch)

Air layers are ready to be removed from the parent plant when the air- layering bags have been permeated by developing roots. Normally this will take 6 to 12 weeks, but may take as long as 2 years.

Most plants can be air layered and, even if no rooting takes place, the original plant is not damaged by the process since you do not remove the donor material until it has produced roots. Herbaceous tropical indoor plants and woody outdoor ornamentals are good candidates for air layering and may include: Rhododendron.

To successfully air layer a plant, you will need to gather: a clean sharp knife, sphagnum moss, polyethylene film, aluminum foil, and twist ties, twine or electricians tape. Rooting hormones may improve rooting success but are not necessary.

The air-layer is then left alone for 3-7 weeks to allow roots to form. The air-layer should be checked after three weeks for root formation. Air layering is a good method of reproducing good-sized plants in one year.

about three months

Disadvantages of Layering: 1) This method of propagation is limited to plants which form growing points readily. 2) It is difficult to produce large number of plants through this method. In other words, this method does not use propagation material economically.

Grafting is considered as a highly useful technique of propagation. Layering is considered as less useful technique of propagation when compared to grafting. With grafting you can get more varieties from a single plant. Layering results in one type of offspring.

Bark grafting can be used on larger rootstock than any other grafting method, so it is the best method to change the variety of a mature tree; the rootstock can be 4 to 12 inches in diameter. Bark grafting is done in early spring when the bark can easily be slipped from the wood, but before there is major sap flow.