Reproduction in Seedless
Plants
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Printed: March 4, 2013
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C ONCEPT
Concept 1. Reproduction in Seedless Plants
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Reproduction in Seedless
Plants
• Explain the reproduction strategies of seedless plants.
Have you ever noticed these little capsules on moss?
These tiny capsules produce spores. This is one stage in the process of reproduction in the mosses. Remember
mosses and other seedless plants do not have flowers, so their life cycle is quite different from other plants.
Reproduction in Seedless Plants
Seedless plants can reproduce asexually or sexually. Some seedless plants, like hornworts and liverworts, can
reproduce asexually through fragmentation. When a small fragment of the plant is broken off, it can form a new
plant.
Reproduction in Nonvascular Seedless Plants
Like all plants, nonvascular plants have an alternation of generations life cycle. That means they alternate between
diploid cell stages (having two sets of chromosomes) and haploid cell stages (having one set of chromosomes)
during their life cycle. Recall the haploid stage is called the gametophyte, and the diploid stage is called the
sporophyte.
In the life cycle of the nonvascular seedless plants, the gametophyte stage is the longest part of the cycle. The
gametophyte is the green photosynthetic carpet that you would recognize as a moss.
The life cycle of nonvascular seedless plants can be described as follows:
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1. The male gametophyte produces flagellated sperm that must swim to the egg formed by the female gametophyte. For this reason, sexual reproduction must happen in the presence of water. Therefore, nonvascular
plants tend to live in moist environments.
2. Following fertilization, the sporophyte forms. The sporophyte is connected to, and dependent on, the gametophyte.
3. The sporophyte produces spores that will develop into gametophytes and start the cycle over again.
Reproduction in Seedless Vascular Plants
For the seedless vascular plants, the sporophyte stage is the longest part of the cycle, but the cycle is similar to
nonvascular plants. For example, in ferns, the gametophyte is a tiny heart-shaped structure, while the leafy plant we
recognize as a fern is the sporophyte.
The fern’s sporangia, where spores are produced, are often on the underside of the fronds (Figure 1.1). Like
nonvascular plants, ferns also have flagellated sperm that must swim to the egg. Unlike nonvascular plants, once
fertilization takes place, the gametophyte will die, and the sporophyte will live independently.
FIGURE 1.1
This fern is producing spores underneath
its fronds.
Vocabulary
• alternation of generations: Describes how plants alternate between diploid-cell and haploid-cell stages
during their life cycle.
• diploid: Having two sets of chromosomes.
• gametophyte: Haploid generation in the life cycle of a plant.
• haploid: Having one set of chromosomes, like sperm and egg.
• sporangia: Capsule in which spores are produced.
• spore: Reproductive structure; can be adapted for dispersal and survival in unfavorable conditions; found in
bacteria, plants, algae, fungi, and some protozoa.
• sporophyte: Diploid generation in the life cycle of a plant.
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Concept 1. Reproduction in Seedless Plants
Summary
• In nonvascular seedless plants, the gametophyte (haploid) stage is the longest part of the cycle.
• In seedless vascular plants, the sporophyte (diploid) stage is the longest part of the cycle.
Practice
Use the resource below to answer the questions that follow.
• Ferns-Pteridophyte Life Cycle at http://www.youtube.com/watch?v=c4YtOT0Z6Ek (12:30)
MEDIA
Click image to the left for more content.
1. Where can the sorus on ferns be found?
2. What is found in the sorus?
3. How is the mechanism that causes spores to be released similar to the mechanism that causes water top move
up xylem? Explain your answer as fully as possible.
4. What is meant by a bisexual gametophyte?
5. What is the affect of the plant hormone antheridiogen? Why is this hormone crucial to ferns?
Review
1. Why must nonvascular plants live in moist environments?
2. Compare and contrast the fern gametophyte and sporophyte.
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