vegetative propagation, the ability of plants to reproduce without sexual reproduction, by producing new plants from existing vegetative structures. Some plants, such as the Canada thistle and most bamboos, send out long underground stems that produce new plants, often at considerable distances from the original plant. Such plants can form enormous colonies of new plants within a relatively few years. Many trees, such as the beech and aspen, send up root sprouts, and large colonies of new trees thus arise. In other trees, the lower branches may produce roots where they rest upon the ground, and new trees are produced. The leaves of some plants produce buds at their edges, which develop in turn into miniature plants that fall off and take root. Specialists in the fields of agriculture and horticulture take advantage of the regenerative ability of plants through such techniques as the rooting of cuttings; grafting and budding of fruit trees; layering, or inducing the tips of branches to produce new plants; the cutting apart of clusters of perennials, such as rhubarb, into individual plants; the cutting of plants (such as the common potato) into pieces that are then planted separately, each with a bud ("eye"); and numerous other techniques. The vegetative propagation of economically important and useful plants is now so widespread that most horticultural varieties are now only reproduced clonally, especially since many of them breed true from seed.