2. Pteridophyta

Spore-Producing Vascular Plants

Ferns

spore-producing vascular plants

Ferns are spore-producing vascular plants that have true leaves, roots, and stems. Ferns are often grown as houseplants.

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The fern's underground stem is a rhizome. Fern rhizomes grow parallel to the surface of the soil. Many small roots grow from the bottom of rhizome.

Young leaves grow from the top of a rhizome. A young, coiled fern leaf is called a fiddlehead. As a fiddlehead grows, it uncoils and develops into a frond, a mature fern leaf.

Some formed ancient forests were tree ferns. Over millions of years, these plants were buried by sand and soil. The mass of the sand and soil produced great pressure and heat.

Eventually the pressure and heat changed the ferns and other plants into coal, oil, and natural gas.

The small, brown spots on the underside of a fern frond are spore cases. This is called a sorus (plural, sori).

Fern Life Cycle

Clusters of spore cases, or sori, on a licorice fern.

Figure:The tiny brown spots on the underside of this fern frond are spore cases.

The curled structures at the tops of these ferns are called fiddleheads. Into what structures do fiddleheads develop?

Sori are produced during the asexual stage of a fern's life cycle. Spores released from the sori are dispersed by wind and water.

The fern's life cycle has two stages. One stage is called the sporophyte stage and the other is called the gametophyte stage. Which stage produces the male and female sex cells

If a spore lands in moist shaded soil, it can germinate and grow into a heart-shaped plant.

The heart-shaped plant is the beginning of the sexual stage of the life cycle. Tiny sex organs form on its underside.

Sperm from the male sex organ swim through water to the female sex organ. A sperm fertilizes an egg, and the zygote grows into an embryo.

The embryo, protected and nourished by the heart-shaped plant, develops into a mature fern. Sori appear on the mature fern, and the cycle begins again.

 Horsetails are spore-producing vascular plants with hollow, jointed stems and scalelike leaves,

Horsetails

Figure: Left: Horsetails in early spring make and disperse spores Right: In late spring, bushy green stems carry on photosynthesis.

Some horsetails change their appearance between spring and summer.

It is a small evergreen plant that looked like the plant. This plant has small mosslike leaves that are closely arranged on its stem. On top of the plant is a club-shaped structure.

Club Mosses

For these reasons, this plant is named a club moss.

Club mosses are spore-producing vascular plants with branching stems and tiny, scalelike leaves.

In fact, some club mosses look so much like young pine trees that people call them ground pine.

Club Moss. Living club mosses are generally small, but prehistoric members of this group were the size of trees

Spores are produced in the club-shaped spore cases at the ends of certain upright branches.

Like ferns and horsetails, club mosses have both an asexual and sexual stage in their life cycle. But the life cycle of a club moss may take as long as 15 years to complete!

1. How do tree ferns that lived in ancient forest affect your life today?2. What organs evolved in ferns that never evolved in bryophytes?

Lesson Review

3. What is the difference between a fiddlehead and a frond? 4. Where would you find the spore case of a horsetail? A club moss?

Interpret and Apply6. Why are most spore-producing vascular plants larger than most bryophytes?

7. A certain fern stops producing spores, eggs, and sperm. Yet, the