Life Cycle of Angiosperms

Angiosperms are flowering plants in which sex organs are present in flowers and seeds are enclosed within fruits. They are highly evolved plants, and their success is mainly due to their efficient sexual reproduction through flowers.

The life cycle of angiosperms shows alternation of generations between two phases.

These two phases are:

• Sporophytic phase (2n): Diploid phase starting from the zygote.
• Gametophytic phase (n): Haploid phase starting from spores.

Angiosperms exhibit a haplodiplontic life cycle. This means that both the diploid sporophyte and haploid gametophyte occur during the life cycle, but the sporophyte is dominant and conspicuous, while the gametophyte is highly reduced.

Sequence of Events

1. The mature flowering plant represents the sporophyte (2n).
2. In the flower, meiosis produces haploid spores (n).
3. Spores develop into male and female gametophytes.
4. These gametophytes produce male and female gametes.
5. Fertilization forms a zygote (2n).
6. The zygote develops into an embryo, then into a seed, and finally into a new sporophytic plant.

Life-cycle of angiosperms

Sporophytic Phase (2n)

The sporophytic phase begins with the zygote and includes the embryo, seedling, and mature flowering plant. This is the dominant, independent, and long-lived phase in angiosperms.

Key features:

• Diploid in chromosome number.
• Starts from the zygote.
• Includes the visible flowering plant body.
• Produces spores by meiosis.
• Dominates the life cycle.

Gametophytic Phase (n)

The gametophytic phase begins with haploid spores and ends with the formation of gametes. In angiosperms, this phase is very short, microscopic, and dependent on the sporophyte.

Key features:

• Haploid in chromosome number.
• Starts from spores.
• Includes male and female gametophytes.
• Produces gametes.
• Highly reduced and short-lived.

• Angiosperms are flowering plants with sex organs in flowers and seeds enclosed within fruits, succeeding mainly through efficient sexual reproduction.
• Their life cycle shows alternation of generations - the diploid sporophytic phase (2n) from the zygote and the haploid gametophytic phase (n) from spores.
• They have a haplodiplontic life cycle in which the sporophyte is dominant and the gametophyte is highly reduced.
• Sporophytic phase (2n): starts from the zygote, includes the embryo, seedling, and flowering plant; dominant, long-lived, and produces spores by meiosis.
• Gametophytic phase (n): starts from spores, forms male and female gametophytes that produce gametes; microscopic, short-lived, and dependent on the sporophyte.