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PinkMonkey Online Study Guide-Biology
15.1 Pteridophyta
Pteridophytes are the simplest of the tracheophytes.
They were abundant in the geological past. Today, they are best represented
by the ferns, although other non-fern pteridophytes are present in lower
abundance.
These plants are usually small and herbaceous. They grow
well in moist, cool, and shady places where water is readily available.
(a) Distinguishing Characteristics
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The life-cycle shows distinct heteromorphic alternation
of generations.
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Diploid sporophyte generation is predominant.
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Sporophyte plant body has true roots, stem and leaves
with well developed vascular system.
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Asexual reproduction takes place by spores.
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Most pteridophytes are homosporous; only a few show
heterospory.
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Spores are produced in multicellular sporangia after
meiosis in spore mother cells.
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Gametophyte is haploid, multicellular, green and
an independent structure.
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Sex organs, antheridia and archegonia are multicellular.
- Antherozoids (sperms) are spirally coiled and multi flagellate.
- Opening of sex organs and transfer of male gametes to archegonium
for fertilization are dependent on water. Further, fertilization takes
place inside the archegonium.
Some common examples of microphyllous pteridophytes (i.e.,
poorly developed leaves) are club mosses (Lycopodium sp.),
and whisk ferns (Psilotum sp.). Examples of megaphyllous (large-leafed)
pteridophytes are the ferns Nephrolepis, Osmunda, Pteris,
and Salvinia.
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Table of Contents
15.0 - Introduction
15.1 Pteridophyta : General Account
15.2
Gymnosperms
15.3
Angiosperms : Dicotyledons
15.4
Angiosperms : Monocotyledons
15.5
Vascularization
15.6
Development of seed habit
15.7
Development of Flower and Fruit
Chapter 16
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