Lycopytes and Sphenophytes
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Lycophytes – club mosses
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Sphenophytes – horsetails
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Appeared more than 400 million years ago.
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Most ancient of the vascular plants.
Ancient Forests
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The Earth’s first forests were composed of these plants.
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The fossilized remains of these plants were transformed into coal beds.
Ferns
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More successful and more complex than the club mosses and horsetails.
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Abundant in wet or seasonally wet habitats throughout the world.
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Grow best in wet tropical areas.
Structures
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True leaves, roots and stems.
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Rhizomes: creeping, underground stems.
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Fronds: large leaves.
Reproductive Structures
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Sporangia: structures found under the fronds which produce spores.
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Sori (sing: sorus): clusters of sporangia.
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Prothallium: green, heart shaped gametophyte.
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Antheridium: produces sperm. Grows on prothallium.
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Archegonium: produces eggs. Grows on prothallium.
Life Cycle
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Alternation of generations.
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Sporophyte is more obvious, dominant stage.
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Spores are produced in sporangia.
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Spores are dispersed by the wind and grow into the prothallium (gametophyte).
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The gametophyte is small and lives for a short time. It lacks vascular tissue and only
grows in moist areas.
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Archegonia (egg production) and antheridia (sperm production) grow on the
gametophyte.
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Fertilization occurs when flagellated sperm SWIM to the eggs.
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Diploid sporophyte grows on gameophtye.
** Water is still required for reproction.