Plant Reproduction

Plant Reproduction

The process by which plants increase their numbers for the next generation, essential for their survival, can be asexual (vegetative means) where all offspring are genetically identical or sexual (involving male and female gametes) where there is the advantage of increasing gentic diversity

Asexual Reproduction

Reproduction method where offspring are genetically identical, achieved through clonal propagation like stem cuttings, tubers, or suckers. Strawberries produce stolon that gives rise to new plants, and Axillary bud on potato tubers gives rise to new plants. The top of a pineapple will grow a new fruit if replanted

Sexual Reproduction

Reproduction involves the fusion of male and female gametes to produce a zygote (embryo) by seed production leading to genetic diversity in offspring. Games are found in the flowers and it requires the transfer of male gamete to the ovules to initiate fertilization

Pollination

The transfer of male pollen to the female stigma, a crucial step for fertilization and seed production, can occur through wind but requires a large amount of pollen each spring or insects when pollen gets stuck to them. Insect-pollinated flowers are attractive and produce nectar to reward the pollinators.

Cross Pollination

Transfer of pollen from one plant's anther to another plant's stigma, often facilitated by insects like bees, promotes genetic diversity. Pollen from the stamens sticks to a bee as it collects food from the flower, then it travels to another plant of the same type and the pollen then sticks to a pistil of a flower on the other plant

Fruit Formation

After pollination, a plant structure containing seeds is formed, not all fruits have seeds like bananas and strawberries but require pollination for fruit development. A flower gives rise to a fruit

Double Fertilization

Unique process where one sperm nucleus fuses with the egg nucleus to form a zygote, while the other fuses with polar nuclei to form endosperm, crucial for embryo development.

Seed Dispersal

For plants to survive, plants must produce lots of seeds and spread them as far as possible to allow them an opportunity for to survive in different environments

Various methods plants use to spread seeds far and wide, including wind dispersals like gass seeds, water dispersals like coconut husks, attachment to animals by making seeds spiny, and enticing animals to eat fruits for seed dispersal so seeds are spread through their droppings

Male gametes

pollen grains and are produced in anthers

Female gametes

Ovules and are produced in the ovary

Pistil

the female organs of a flower comprised of the stigma, style and ovary

Steps in fertilization

1. The pollen grain has 2 sperm nuclei, which germinate the stigma of the same plant species and produce a germ tube

2. The germ tube grows down the style reaches the ovary and looks for the opening called a micropyle

3. One sperm nucleus fuses with the egg nucleus inside the ovule to form the zygote (2n) and the second sperm nucleus fuses with the 2 polar nuclei to form the endosperm which is the food storage for the developing embyro

Development of the zygote

The zygote divides several times to form an embryo which then differentiates to form a root and shoot apex. The ovary expands and the walls become the seed coat.

Each fertilized ovule forms 1 seed, plants have can have 1 seed like an avocado or multiple like peas and corn

The ovary walls can be fleshy like a peach. Each seed has 1 or 2 cotyledons depending if its a monocot or dicot plant species

The seeds will germinate to form a shoot and shoot and that plant has now be propagated sexually