http://www.tutorvista.com/biology/natural-vegetative-reproduction
Bulbs consist of very short stems with closely packed
leaves arranged in concentric circles round the stem.
These leaves are swollen with stored food e.g. onion.
A terminal bud will produce next year’s flowering shoot
and the lateral (axillary) buds will produce new plants.
Corms also have a short stem but in this case it is the
stem itself which swells and stores food. The circular
leaves form only papery scales. As with bulbs, the
terminal bud grows into a flowering shoot and the lateral
buds produce new plants.
http://www.biology-resources.com/plants-vegetative-reproduction.html
http://www.tutorvista.com/biology/natural-vegetative-reproduction
Rhizomes are stems which grow horizontally under the
ground. In some cases the underground stems are
swollen with food reserves e.g. iris. The terminal bud
turns upwards to produce the flowering shoot and
the lateral buds may grow out to form new rhizomes.
Runners are also horizontal stems growing from the
parent plant, but they grow above ground. When their
terminal buds touch the ground they take root and produce new plants.
Advantages of vegetative reproduction
Since food stores are available throughout the year and the parent plant with its root system can absorb water from quite a wide area, two of the hazards of seed germination are reduced. Buds are produced in an environment where the parent is able to flourish, but many seeds dispersed from plants never reach a suitable situation for effective germination. Vegetative reproduction does not usually result in rapid and widespread distribution of offspring in the same way as seed dispersal, but tends to produce a dense clump of plants with little room for competitors between them. Such groups of plants are very persistent and, because of their buds and underground food stores, can still grow after their foliage has been destroyed by insects, fire, or cultivation. Those of them regarded as weeds are difficult to eradicate, since even a small piece of rhizome bearing a bud can give rise to a new colony (clone).
