Reproduction in Plants
Reproduction is the biological process by which new individual organisms are produced and there are different modes of reproduction in plants.
Flowers are the reproductive parts of the plants. A flower may have either the male part or the female part or both male and female parts. The flowers, which contain either only the pistil or only the stamens are called unisexual flowers, while which contain both stamens and pistil are called bisexual flowers.
Reproduction in plants is categorized into two types: Asexual reproduction and Sexual reproduction
In asexual reproduction, plants can give rise to new plants without involvement of seeds. Types of asexual reproduction in plants include vegetative propagation, budding, fragmentation and sporulation.
Vegetative Propagation is a process through which new plant arise from roots, stems, leaves and buds, without production of seeds or spores. The roots of some plants can also give rise to new plants for e.g. sweet potato.
Plants produced by vegetative propagation take less time to grow and bear flowers and fruits earlier than those produced from seeds.
Budding is a process in which a small outgrowth called bud develops on one of the vegetative organs. This bud then grows and matures into an adult organism.
Yeast grow and multiply every few hours by budding if sufficient amount of nutrients are available.
In fragmentation, an organism is split into fragments, and each fragment develops into a mature organism. E.g., algae grow and multiply by fragmentation in the presence of water and sufficient nutrients.
Spores are asexual reproductive bodies that germinate and develop into a new individual. Each spore is covered by a hard protective coat to withstand unfavorable conditions. Plants such as moss and ferns reproduce by means of spores.
In sexual reproduction, a male and a female gamete fuse to form a zygote, which develops into an adult plant eventually. In plants, stamens are the male parts and pistil is the female reproductive part. The anther contains pollen grains which produce male gametes while female gamete or the egg is formed in ovary.
Pollination is the transfer of pollen from the anthers to the stigma. This can occur with the help of various agents such as wind, water, insects etc. Some flowers show self-pollination, when pollen and pistil are from the same plant, often (but not always) from the same flower. While some plants exhibit cross-pollination in which pollen and pistil must be from different plants.
Fertilisation refers to the fusion of male and female gametes to form a zygote. The zygote develops into an embryo, which grows and develops inside the seed. When the seed has the fully matured embryo, it germinates.
After fertilisation, the ovary grows into a fruit while seeds develop from the ovules.
Fruits have nutrients that attract dispersing agents. Seed dispersal enables the plants to invade new habitats for wider distribution. Seed dispersal is facilitated by wind, water and animals etc. Castor and balsam seeds are dispersed when the fruits burst with sudden jerks.