Reproduction in plants

Start music   Jan 6 2017 || 12:45 PM

Reproduction

  • Production of new individuals from their parents is known as reproduction

 

Parts of a plant

  1. Vegetative part (roots, stems and leaves)
  2. Reproductive part (flowers)

 

Type of reproduction

  • Asexual reproduction – plants give rise to new plants without seeds
  • Sexual reproduction – new plants are obtained from seeds

 

Asexual reproduction

Vegetative propagation

  • Reproduction is through the vegetative parts of the plant (roots, stem, leaf or bud)
  • Thus it is known as vegetative propagation.
  • Eg: Stem cutting of rose, Buds in the margins of leaves of Bryophyllum, Roots of sweet potato
  • Plants produced by vegetative propagation take less time to grow and bear flowers and fruits earlier than those produced from seeds
  • The new plants are exact copies of the parent plant

 

Budding (Yeast)

  • The small bulb-like projection coming out from the yeast cell is called a bud
  • The bud gradually grows and gets detached from the parent cell and forms a new yeast cell

 

Fragmentation (Algae)

  • An alga breaks up into two or more fragments.
  • These fragments or pieces grow into new individuals
  • When water and nutrients are available algae grow and multiply rapidly by fragmentation

 

Spore formation

  • The spores are asexual reproductive bodies.
  • Each spore is covered by a hard protective coat to withstand unfavourable conditions such as high temperature and low humidity.
  • Under favourable conditions, a spore germinates and develops into a new individual.
  • Plants such as moss and ferns reproduce by means of spores

 

Sexual reproduction

Reproduction involving the fusion of a male and a female gamete

 

Flowers

  • Flowers having both stamens (male reproductive part) and pistil (female reproductive part), are called bisexual flowers
  • Flowers having only one, either male or female parts are unisexual flowers
  • Anther contains pollen grains which produce male gametes
  • The egg/female gamete is formed in the ovule

 

Pollination

  • The transfer of pollen from the anther to the stigma of a flower is called pollination
  • Pollen grains have a tough protective coat which prevents them from drying up.
  • They get carried by wind, water or even insects

Self-Pollination

  • If the pollen lands on the stigma of the same flower

Cross-Pollination

  • If the pollen of a flower lands on the stigma of another flower of the same plant, or that of a different plant of the same kind

 

Fertilisation

  • The male and female gamete fuse to form the zygote
  • The process of fusion of male and female gametes (to form a zygote) is called fertilisation
  • The zygote develops into an embryo.

 

Fruit and seed formation

  • After fertilisation, the ovary grows into the fruit and other parts of the flower fall off.
  • The seeds develop from the ovules.
  • The seed contains an embryo enclosed in a protective seed coat.

 

Seed Dispersal

  • Seeds are dispersed by wind, water, animals and even humans
  • Seed dispersal helps the plants to
    • Prevent overcrowding,
    • Avoid competition for sunlight, water and minerals
    • Invade new habitats