Natural vegetative propagation
At the core vegetative propagation plants lies in their widespread ability to regeneration, that is, to the renewal of lost organs or parts, or in general to the development of the whole plant again from separate parts of the body. In animals, the ability to regenerate is the stronger, the lower the animal is in the system.
Among plants in the lower groups, which have less cell differentiation, the ability to regenerate is also greater, for example, even in many mosses, almost any cell in their body is potentially capable of developing a new plant. But even in many seed plants, very small parts of their body, mainly the root, underground or above-ground shoots (not leaves), are also capable of producing a new plant. Moreover, in more rare cases, renewal occurs directly at the site of injury; more often, somewhere near the wound, a neoplasm occurs or the wound causes the growth of organs already laid down, but which were in their infancy.
In unicellular plants, their reproduction by cell division can be considered vegetative propagation. Multicellular and large non-cellular algae, fungi, lichens often reproduce vegetatively, by accidental, but, undoubtedly, often breaking off individual sections from their thallus, which, due to their extraordinary ability to regenerate, develop into new plants.
In mushrooms, mosses, club mosses, selaginella in the simplest cases, vegetative reproduction consists in the fact that the old parts of the thallus or shoot die off, while its younger branches stand apart and become independent.
In ferns, horsetails in a similar way, the old sections of the underground rhizomes die off and the young ones are isolated with the above-ground shoots that have developed from them. In addition, in some of these higher spore plants, vegetative reproduction occurs with the help of the so-called brood buds- adnexal buds on the leaves, which, falling off the mother plant, germinate and give rise to new individuals.
Among seed plants only annuals and biennials do not reproduce vegetatively in natural conditions. Among perennials, almost all herbaceous and many woody are capable of vegetative propagation in one way or another.
In the simplest cases, in relatively few cases, this occurs by detaching shoots from the mother plant, developing into a new individual. In duckweed, in this way, from several overwintered specimens, offspring are formed in a few weeks, covering an area of \u200b\u200bhalf a hectare. In this regard, probably, duckweed rarely blooms. In elodea, each easily broken off piece of stem can develop into a new plant.
The most widespread in seed plants is vegetative propagation through rhizomes, above-ground creeping and rooting shoots, bulbs, adventitious buds on roots.
Aboveground creeping shoots (lashes, whiskers, stolons) ecologically represent the transition from typical upright stems to rhizomes. Creeping along the surface of the earth, they form adventitious roots in the nodes and here, in the axils of the leaves, buds that give vertical, leafy shoots. The internodes of creeping shoots die off, and new plants lose their connection with the parent. In this way, strawberries, stone fruits, some cinquefoils, creeping tenacity, budra and others reproduce. The length of the annual growth of each lash ranges from 4 cm (for some saxifrage) to 1.5 m (for strawberries) and above. From one strawberry plant in two years, 200 plants can be formed in this way, occupying a decent area.
Vegetative propagation of strawberries by aboveground creeping shoots:
rhizomes vegetative reproduction occurs in most perennial grasses. On short rhizomes, the buds are brought together, and crowded above-ground shoots are obtained. On long rhizomes, the buds are not crowded, and the above-ground shoots formed from them are not close together. As the old rhizomes rot, the new plants become quite independent. Growing in all directions, long-rhizome grasses quickly populate a large area.
The length of the annual growth of rhizomes reaches 5-10 cm for lute anemone, oregano, 10-15 cm for yarrow, horsetail, 25-30 cm for couch grass, gout grass - 25-30 cm, Ivan tea - 85-100 cm, podbela - 100 -150 cm, Sakhalin buckwheat - 150-300 cm.
Thanks to vegetative reproduction by rhizomes, the species composition of our meadows, which are usually mowed during the flowering of cereals, almost does not change. Some rhizomatous plants (for example, creeping wheatgrass, gout grass, and others) in crops are difficult to eradicate weeds.
Reproduction by underground shoots:
bulbs many herbaceous, mainly monocotyledonous plants from the Liliaceae and Amaryllis families (onions, garlic, tulips, hyacinth, narcissus, lilies, goose onions and others) reproduce. In some bulbs, bulbs are also formed in the axils of the leaves of above-ground stems (in Lilium bulbiferum, teeth) or in inflorescences (in Allium oleraceum,Allium cordoprasum, garlic, etc.); in the latter case, flowers are formed much less or not at all.
tubers, serving for vegetative propagation, are of stem and root origin, moreover, both can be underground and aboveground.
Very common vegetative propagation accessory kidneys, formed on the roots and developing into above-ground shoots, the so-called root suckers. New plants become completely independent after the death of the roots that connected them with the mother.
Many plants form such root shoots.
The following example shows how enormous the capacity of plants for vegetative reproduction can be. In Norway, rhizomes and roots of weeds were found per 1 ha, on which buds were capable of developing: purple sow thistle, or budyak, - 5.25 million, field (yellow) sow thistle - 16.6 million, coltsfoot - about 26 million, couch grass - about 260 million. For comparison, it should be noted that no more than 3-4 million grains of wheat are sown per 1 ha.
In some plants, in the axils of the leaves, in the inflorescences, instead of flowers, small leafy shoots are formed ( brood buds), which then fall off the mother plant and take root. Sometimes these plants are called viviparous, since it was previously mistakenly believed that their seeds germinate on the mother plant. They are distributed mainly in polar, high-mountainous or steppe areas, where, due to the shortness of the growing season, the seeds may not ripen. These are the steppe bluegrass (Poa bulbosa), some saxifrage (Saxifraga nivalis,Saxifraga cernua), stonecrop (Sedum villosum,Sedum dasyphyllum), rushes (Juncus supinus,Juncus alpinus), some arctic fescue ( Festuca) and others.
In many aquatic, mainly floating plants, in autumn, special wintering buds, which are filled with starch and sink to the bottom either together with the mother plant, or separated from it. In the spring, after the mother plant rots, they float up due to the development of air cavities and develop into new plants. This is how overwintering and vegetative reproduction occur in pemphigus, telorez, frog, urut, some pondweeds and others.
Root shoots - shoots formed from dormant buds of plant roots;
Bulbs;
Root tubers, or modified roots - receptacles of nutrients. Root tubers themselves are unsuitable for reproduction, since they do not have dormant buds, like real tubers of stem origin. Therefore, they are separated with a piece of the root collar with one or two buds;
Stem tubers. There are stem tubers with limited growth, that is, they stop growing at the end of the growing season, and stem tubers with continued growth in subsequent growing seasons.
Bulbous plants are divided into two groups: evergreen and deciduous, the latter, in turn, according to the location of the onion-children, are divided into underground, aerial - stem, located in the axils of the leaves, and in the form of inflorescences filled with bulbs.
