The most common are by taking cuttings and rooting them (usually with the aid of a rooting hormone), and grafting (which is more involved, and more difficult to do.) Google "plant propagation...
Man-made methods of vegetative reproduction are usually enhancements of natural processes, but range from simple cloning such as rooting of cuttings to grafting and artificial propagation by...
Plants are autotrophs, meaning they make their own food - plants use the energy from sunlight to create sugar, which they then use for metabolic energy. Other nutrients are drawn from either the soil...