Angiosperm Life Cycle - Overview, Defination, Stages

What Are Angiosperms?

They hold the record as the most diversified and widely distributed group of plants; flowering plants are characterised by their seeds enclosed within fruits. They range from minute herbs to large trees and number well over 300,000 species. More than others, angiosperms hold a very significant place in this ecosystem, because they are producers of the environment, providing food and shelter to other creatures.

They also play very key roles to humans, since they provide us with basic needs such as food, drugs, clothing, and raw materials. Angiosperm life cycles are examples of generation alteration, with the life cycle being dominated by sporophytes. It begins when a seed germinates, and develops into a mature plant, flowers, pollination, fertilisation, and seed formation, to complete the life cycle and continue the species.

Life Cycle Stages

The life cycle stages of seed development are described below-

Seed Stage

Structure of a Seed (Monocots vs. Dicots)

The seed consists of an embryo, a seed coat, and stored food. Monocot seeds have one cotyledon, and dicots have two.

Seed Germination Process

A seed germinates to a new plant by the process of imbibition, enzyme activity and sprouting of radicle and plumule.

Seedling Stage

Development of Root and Shoot

The root system develops during the seedling stage, provides anchorage and nutrient absorption, and the shoot system grows upward to initiate photosynthesis.

Vegetative Growth Stage

Leaf Development

The leaves develop and emerge and increase the surface area of the plant necessary for photosynthesis.

Photosynthesis and Plant Growth

Photosynthesis is the process by which light energy is converted to chemical energy and it is what avails the requirements for a plant's growth and development.

Reproductive Stage

Flower Development

Flowers' development happens while a plant is shifting to reproduction. They have structures that are going to generate gametes.

Pollination

Self-pollination happens in the same flower or plant and cross-pollination is in a different plant.

Fertilisation

The process of combining male and female gametes to form a zygote.

Double Fertilization Process

One of the sperms fertilises an egg, and another with two polar nuclei forms the endosperm.

Fruit And Seed Development

Formation of Fruit

After fertilisation, the ovary develops into fruit. Fruits protect the seeds and aid in their dispersal.

Seed Dispersal Mechanisms

Wind, water, animals and mechanical ejection disperse seeds.

Detailed Process Of Fertilisation

The fertilisation process is described below-

Pollen Tube Formation

If a pollen grain arrives at the stigma of a compatible flower, it germinates and grows to develop a pollen tube. Aided by some chemical signals, this tube grows down through the style to the ovary and discharges male gametes, and sperm, which reach the ovule.

Fusion Of Gametes

Of the mature ovule, but this occurs through a pore the micropyle, in the old ovule. In its tip, the pollen tube contains two sperms; one of the sperms fuses with the egg cell to form a zygote, and the other one fuses with the two polar nuclei to form the triple-cell that matures into the endosperm.

Formation Of Zygote And Endosperm

The fertilised egg cell, or zygote, divides by mitosis to become the embryo that, eventually will develop into the new plant. The triploid cell, formed by the fertilisation of the second sperm with the two polar nuclei, becomes the endosperm and will feed the embryo being formed.