Everything about Vegetative Reproduction totally explained
Vegetative reproduction is a type of
asexual reproduction found in plants, and is also called
vegetative propagation or
vegetative multiplication. It is a process by which new
plant "individuals" arise or are obtained without production of
seeds or
spores. It is both a natural process in many plant species (including organisms that may or may not be considered "plants", such as bacteria and fungi) and one utilized or encouraged by
horticulturists to obtain quantities of economically valuable plants.
Natural vegetative reproduction is mostly a
process found in
herbaceous and
woody
perennial plants, and typically involves structural modifications of the
stem, although any horizontal, underground part of a plant (whether stem or a
root) can contribute to vegetative reproduction of a plant. And, in a few species (such as
Kalanchoë shown at right),
leaves are involved in vegetative reproduction. Most plant species that survive and significantly expand by vegetative reproduction would be perennial almost by definition, since specialized organs of vegetative reproduction, like seeds of annuals, serve to survive
seasonally harsh conditions. A plant that persists in a location through vegetative reproduction of individuals over a long period of time constitutes a
clonal colony.
In a sense, this process isn't one of "reproduction" but one of survival and expansion of biomass of the individual. When an individual
organism increases in size via cell multiplication and remains intact, the process is called "vegetative growth". However, in vegetative reproduction, the new plants that result are new individuals in almost every respect except genetic. And of considerable interest is how this process appears to reset the
aging clock.
Natural vegetative structures
The
rhizome is a modified underground stem serving as an organ of vegetative reproduction, for example
Polypody.
Prostrate aerial stems, called
runners or
stolons are important vegetative reproduction organs in some species, such as the
strawberry, numerous
grasses, and some
ferns.
Adventitious buds form on roots near the ground surface, on damaged stems (as on the stumps of cut trees), or on old roots. These develop into above-ground stems and leaves.
A form of budding called
suckering is the reproduction or
regeneration of a plant by shoots that arise from an existing
root system. Species that characteristically produce suckers include
Elm (
Ulmus),
Dandelion (
Taraxacum), and members of the
Rose Family (
Rosa).
Another type of a vegetative reproduction is the production of
bulbs. Plants like
onion (
Allium cepa),
hyacinth (
Hyacinth),
narcissus (
Narcissus) and
tulips (
Tulipa) reproduce by forming bulbs.
Other plants like
potatoes (
Solanum tuberosum) and
dahlia (
Dahlia) reproduce by a method similar to bulbs: they produce
tubers.
Gladioli and
crocuses (
Crocus) reproduce by forming a bulb-like structure called a
corm.
Exceptions
Vegetative propagation is usually considered a cloning method. However, there are several cases where vegetatively propagated plants are not genetically identical. Rooted stem cuttings of thornless blackberries will revert to thorny type because the adventitious shoot develops from a cell that's genetically thorny. Thornless blackberry is a
chimera, with the epidermal layers genetically thornless but the tissue beneath it genetically thorny. Leaf cutting propagation of certain chimeral variegated plants, such as snake plant, will produce mainly nonvariegated plants.
Grafting is often not a complete cloning method because sexual seedlings are used as rootstocks. In that case only the top of the plant is clonal. In some crops, particularly apples, the rootstocks are vegetatively propagated so the entire graft can be clonal if the scion and rootstock are both clones.
Apomixis is a type of sexual reproduction involving unfertilized seeds.
Hawkweed (
Hieracium),
dandelion (
Taraxacum), some
Citrus (
Citrus) and
Kentucky blue grass (
Poa pratensis) all use this form of asexual reproduction. Bulbils are sometimes formed in the flowers of
garlic. The leafy crown of a
pineapple fruit will root to form a new plant. These cases wouldn't be vegetative reproduction because normally reproductive parts were involved. They would be considered asexual reproduction however. Vegetative reproduction involves only vegetative structures, for example roots, stems or leaves.
Horticultural aspects
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 laboratory
tissue cloning. It is very commonly practised to propagate
cultivars with individual desirable characteristics.
Fruit tree propagation is frequently performed by budding or grafting desirable cultivars (
clones), onto
rootstocks that are also clones, propagated by
layering.
In horticulture, a "cutting" is a branch that has been cut off from a mother
plant below an
internode and then rooted, often with the help of a
rooting liquid or powder containing
hormones. When a full root has formed and leaves begin to sprout anew, the clone is a self-sufficient plant, genetically identical to the mother plant. Examples are cutting from the stems of
blackberries (
Rubus occidentalis), cutting from leaves of
African violets (
Saintpaulia), and cutting the stems of
verbenas (
Verbena) to create new plants. A related form of regeneration is that of
grafting. This is a process of taking a bud and grafting onto a plants stem. Many
nurseries now sell trees that can produce four or more varieties of
apples (
Malus spp.) from stems grafted to a common rootstock.
Cultivated plants propagated by vegetative methods
A number of commonly cultivated plants are propagated by vegetative means rather than by seeds. This is a listing of such plants:
» Apple
Avocado » Banana
Cacao » Canna
Cannabis » Citrus (
lemon,
orange,
grapefruit)
Date » Fig
Grapes » Manioc (cassava)
Nut crops (
walnut,
pecan)
» Pineapple
Pear » Poplar
Potato » Strawberry
Sugar cane » Tea
Vanilla » Willow
Further Information
Get more info on 'Vegetative Reproduction'.
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