Plants Reproduction

Plant Reproduction

Plant reproduction is the production of new individuals or offspring in plants, which can be accomplished by sexual or asexual means. Asexual reproduction produces new individuals without the fusion of gametes, genetically identical to the parent plants and each other. In seed plants, the offspring can be packaged in a protective seed, which is used as an agent of dispersal.

Sexual Reproduction

Sexual reproduction in plants involves male and female plant organs. The female structures invovled in sexual reproduction are the stigma, the style and the ovary. The stigma is the sticky portion of the pistil that captures pollen. The style is long and slender and supports the stigma. The ovary is composed of one or moreovules and is responsible for housing the eggs. The male structures involved in sexual reproduction are the filament and the anther. The filament supports the anther which is responsible for storing and producing pollen. Pollination is the transfer of pollen from an anther to a stigma. Wind, water, insects, birds, and small mammals all aid in the pollination of plants. After pollination, one nuclei of the pollen grain forms a tube down through the style to the micropyle of the ovary. The second nuclei travels down the tube and splits into two sperm nuclei that fertilize the egg and combine with polar bodies to form the endosperm (stored fruit). 

Function of floral parts

Sepal:To protect the flower and prevent it from drying out.

Petals:To attract insects or other pollinators to the plant for sexual reproduction.

Asexual Reproduction

All plant organs have been used for asexual reproduction, but stems are the most common.

In some species, stems arch over and take root at their tips, forming new plants.

Above-ground stems

The horizontal above-ground stems (called stolons) of the strawberry (shown here) produce new daughter plants at alternate nodes.

Underground stems

• rhizomes
• bulbs
• corms and
• tubers

Leaves

Leaves of the common ornamental plant Bryophyllum (also called Kalanchoë)  produce tiny plantlets along the leaf margin that fall off and can take up an independent existence

Roots

Some plants use their roots for asexual reproduction. The dandelion is a common example. Trees, such as the poplar or aspen, send up new stems from their roots. In time, an entire grove of trees may form — all part of a clone of the original tree.

Plant Propagation

Commercially-important plants are often deliberately propagated by asexual means in order to keep particularly desirable traits (e.g., flower color, flavor, resistance to disease).Cuttings may be taken from the parent and rooted.


Grafting is widely used to propagate a desired variety of shrub or tree. All apple varieties, for example, are propagated this way.
Apple seeds are planted only for the root and stem system that grows from them. After a year's growth, most of the stem is removed and a twig (scion) taken from a mature plant of the desired variety is inserted in a notch in the cut stump (the stock). So long the cambiums of scion and stock are united and precautions are taken to prevent infection and drying out, the scion will grow. It will get all its water and minerals from the root system of the stock. However, the fruit that it will eventually produce with be identical (assuming that it is raised under similar environmental conditions) to the fruit of the tree from which the scion was taken.