Natural Vegetation by Leaf

The leaf of Bryophyllum has notches on its margin. When this leaf is mature, or falls on the ground, the adventitious buds appear in the notches with adventitious roots. These grow in new plants.

Vegetative Propagation in Flowering Plants

In plants, vegetative propagation takes place both naturally and artificially.
Natural vegetative propagation (asexual method) involves the vegetative parts of a flowering plant such as stem, leaves etc.
Natural vegetative propagation takes place by these two methods a) By stem and b) By leaves
BY STEM: common methods of vegetative propagation by stem are runners and suckers.
RUNNERS: A runner is a long and thin stem, which creeps along the surface of the soil. It gives off adventitious roots at nodes, which may separate from the parent plant to give rise to a new plant.
Examples are grasses, strawberry etc.
SUCKERS: Suckers are lateral branches of the stem with terminal buds and grow from the base of underground stems of certain plants. They grow obliquely to the soil level and produce new aerial shoots with adventitious roots, establishing new daughter plant e.g. mind, and banana.

Asexual Reproduction in Rhizopus

Rhizopus reproduces asexually by the formation of spores in sporangia.
Spores are single celled and thick-walled. They are produced in sporangium, which are born on the tips of sporangiophores. The spores are released from the sporangium and dispersed by wind. When each spore finds suitable conditions, it germinates to form new mycelium of Rhizopus.

Asexual Reproduction in Yeasts

As we know that yeast is a fungus and it consists of a single microscopic spherical cell, which reproduces by budding.
During budding, a small bud or outgrowth is formed on one side of the cell. The nucleus divides by mitosis into two nuclei and one of the nuclei floats in the bud.
Bud enlarges and is finally cut off as an independent cell. When the process of budding is rapid, the individuals formed, do not separate at once and as a result, small groups of attached cells may sometime be seen.

Asexual Reproduction in Bacteria

Bacteria reproduce asexually through binary fission in which they divide into two by simple division under favorable conditions.
Binary fission takes place about every 20 minutes. Bacteria have a single circular chromosome made of DNA.
When the DNA molecule replicates, it results in the formation of two chromosomes.
The two chromosomes move towards opposite sides.
The middle portion of the cell membrane invaginates inwards inward from the two sides and when meet in the center it separates the two halves of the bacterial cell.
New cell-wall is deposited between two cross cell membranes.
The daughter bacteria grow to their normal size, and then separate from one another.

Sexual Reproduction

Sexual reproduction is a method to produce individuals with the involvement of gametes.
Genetic variability is produced by sexual reproduction due to the meiosis and mixing of hereditary material. This genetic variability helps the organisms to live successfully in changing environment. So, some of the offspring would survive, even if most of them are wiped off by a particular disease, because the surviving organisms have the resistance to that disease.