2. Pteridophyta

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2. Pteridophyta
Spore-Producing Vascular Plants
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Ferns
spore-producing vascular plants
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Ferns are spore-producing vascular plants that
have true leaves, roots, and stems. Ferns are
often grown as houseplants.
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The parts of a fern
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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.
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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.
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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.
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Eventually the pressure and heat changed the
ferns and other plants into coal, oil, and
natural gas.
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The small, brown spots on the underside of a
fern frond are spore cases. This is called a
sorus (plural, sori).
Fern Life Cycle
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Clusters of spore cases, or sori, on a licorice
fern.
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FigureThe tiny brown spots on the underside of
this fern frond are spore cases.
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The curled structures at the tops of these ferns
are called fiddleheads. Into what structures do
fiddleheads develop?
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Sori are produced during the asexual stage of a
fern's life cycle. Spores released from the sori
are dispersed by wind and water.
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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
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If a spore lands in moist shaded soil, it can
germinate and grow into a heart-shaped plant.
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The heart-shaped plant is the beginning of the
sexual stage of the life cycle. Tiny sex organs
form on its underside.
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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.
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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.
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 Horsetails are spore-producing vascular plants
with hollow, jointed stems and scalelike leaves,
Horsetails
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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.
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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
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For these reasons, this plant is named a club
moss.
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Club mosses are spore-producing vascular plants
with branching stems and tiny, scalelike leaves.
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In fact, some club mosses look so much like young
pine trees that people call them ground pine.
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Club Moss. Living club mosses are generally
small, but prehistoric members of this group were
the size of trees
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Spores are produced in the club-shaped spore
cases at the ends of certain upright branches.
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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!
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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
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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?
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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