This document describes the life cycle of ferns. It explains that ferns reproduce asexually through spores and sexually through gametophytes. The spores grow into heart-shaped prothalli that produce male antheridia and female archegonia for fertilization. Fertilization results in a diploid zygote that develops into a new fern sporophyte, completing the alternation of generations.

1. Pteridophyta (Fern)
PREPARED BY: DAMBAR SINGH KHATRI
PRAKASH SECONDARY SCHOOL
BENI, MYAGDI
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2. Behavioral objectives
Students will be able to -
Describe the morphology of fern plant.
Explain the asexual and sexual reproduction in fern plant.
Summarize the alternation of generation in fern plant.
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3. Instructional materials
Ppt slide, projector
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4. Introduction
Commonly found in moist and shady places in tropical to temperate region.
Some are fond in aquatic habitat as epiphyte i.e. growing on trunk of trees.
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5. The plant body is sporophytic and differentiated into root, stem, and leaf. The root is fibrous
and arises from stem.
The stem is underground horizontally placed, branched or unbranched.
Its colour is dark brown. It is called rhizome. It is covered by brown hairs called remanta which
protects young leaves from the injury and drying.
The leaf is aerial part. It consists of thick and stout petiole. On the either side of rachis, pinnae
are present. The young leaves are curved and called circinate leaves.
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6. Life cycle
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7. The fern plant is sporophytic that produces spores. The spores are unicellular uninucleated thick
walled and dusty appearance. The spores are produced within sporangia. Each sporangium has a
short stalk and capsule covered by single layer of cells called jacket.
The capsule has some flat cells called annulus and a demarcation for break called stomium. The
spores are formed within capsule. In dry condition annulus contract, loosing water and
sporangium or capsule ruptured through stomium and spores are released out.
Sporangia are found in a group. The group is called sorus. Sori are found on the ventral surface
of pinnae. Pinnae, which bear sori, are called sporophylls.
The sori usually dark brown in colour and are round patches arranging on ventral leaf surface.
The sporangia are arranged on either side of placenta and are covered by indusium.
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8. Spore Germination:
Under favorable condition in soil, spores germinate by producing small tube called germ tube.
The germ tube undergoes mitotic division to form uniseriate filament.
Rhizoids are developed at the base of uniseriate filament. Uniseriate filament undergoes
multiple divisions and develops into heart shaped structures called prothallus. Mature
prothallus bears rhizoids at the base on ventral surface.
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9. Gametophyte:
The prothallus produced by germination of spore is called gametophyte, which forms male and
female sex organs.
The male sex organs - Antheridia and female sex organs - archegonia are also found developed
on the ventral surface of the prothallus. The archegonia are situated below apical notch and the
anheridia are situated on the posterior end of prothallus.
The mature prothallus is green small multicellular and dorsoventrally flattened.
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10. Sexual reproduction:
The prothalus is monocuous. The antheridia are small, globular, and sessile.
The antheridia remains covered by layer called jacket, which encloses antherozoids.
Each antherozoids are coiled multiflagellated with posterior vesicle. Vesicle helps to swim in
water. The antherozoids or male gametes come out when anteridial wall gets ruptured.
The archegonia are small flask shaped and multicellular. The neck of archegonia consists of one
binucleate neck canal cell and the Venter consists of one Venter canal cell and egg or ovum.
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11. Fertilization:
The antherozoids reach to the apex of archegonia by swimming in water. The antherozoids get
the way through neck when the neck canal cell and Venter canal cell dissolved and fused with
egg.
The zygote is formed which is diploid. The zygote undergoes multiple divisions and develops into
embryo. Form embryo root stem and leaves develop and new fern plant is produced. From the
anterior superior region stem arises leaves arise from anterior inferior region and root arises
from the posterior region. After development of embryo, the prothallus decays, and
gametophytic generation is finished.
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12. Assessments
Where is the habitat of fern plants.
Name the parts of fern plants.
Tell the structure of sporangium.
Which cell division takes place during spore formation?
What is the structure of prothallus?
Tell the structure of antheridium?
What is the structure of Archegonium?
What is alternation of generation?
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13. Assignments
Draw the well labelled diagram of fern plants?
Collect the fern(Dryopteris) plants presents nearby in your locality and observe the sorus.
Make a brief notes on alternation of generation in dryopteris.
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