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9.3: Plant Life Cycle Overview

How do plants reproduce?

Is it really due to the birds and the bees? Not always. Even though it is spotted, this plant is known as the kangaroo fern, not the cheetah fern. And all those spots are spores. So what's a spore? Each spore can grow into a new individual without the need for fertilization.

Life Cycle of Plants

All plants have a characteristic life cycle that includes alternation of generations. Plants alternate between haploid and diploid generations. Alternation of generations allows for both asexual and sexual reproduction. Beginning with the diploid sporophytespores form from meiosisAsexual reproduction with spores produces haploid individuals called gametophytes, which produce haploid gametes by mitosis. Sexual reproduction with gametes and fertilization produces the diploid sporophyte. A typical plant’s life cycle is diagrammed in Figure below.

Life cycle of plants

Life Cycle of Plants. This diagram shows the general life cycle of a plant.

Early plants reproduced mainly with spores and spent most of their life cycle as haploid gametophytes. Spores require little energy and matter to produce, and they grow into new individuals without the need for fertilization. In contrast, most modern plants reproduce with gametes using pollen and seeds, and they spend most of their life cycle as diploid sporophytes. Many modern plants can also reproduce asexually using rootsstems, or leaves. This is called vegetative reproduction. One way this can occur is shown in Figure below.

Strawberry plants have horizontal stems called stolons that can form new plants.

Strawberry plants have horizontal stems called stolons that run over the ground surface. If they take root, they form new plants.




  • All plants have a characteristic life cycle that includes alternation of generations.
  • Asexual reproduction with spores produces a haploid gametophyte generation.
  • Sexual reproduction with gametes and fertilization produces a diploid sporophyte generation.


  1. Define alternation of generations.
  2. What type of reproduction occurs in an alternation of generations life cycle?
  3. Draw a diagram of a typical plant life cycle that illustrates the concept of alternation of generations.