Pteridophyta-Fern-Dryopteris | uksir-notes | Diversity-Living-World7
Diversity in Living World 7
 |
| Fern |
Want to know about Bryophyte, Click the Link below:
Want to know about Kingdom of Plantae Algae , Click the Link below:
https://uksirnotes.blogspot.com/2022/09/Kingdom-Plantae-Algae-Spirogyra-uksir.html
Pteridophyta:
General characters :
- Feather like plant. Term was given by Haeckel.
- Commonly called as Ferns.
- 1st true terrestrial plants.
- Seedless vascular plant with distinct Leaf, stem and roots.
- Developed from Bryophytes.
- Mostly found at Wet, Moist and shady places.
- Plant body is saprophytic (2n) may be Megaphyllus (Large leaves) Or Microphyllus (Small leaves)
- Differentiated into leaf, stem and root.
- Vascular tissue developed, but xylem with out vessel and phloem with out companion cell.
- Secondary growth absent.
- Vegetative reproduction – Bulbils, Fragmentation, adventitious buds etc.
- Asexual reproduction- by Spores.
- Spore produced inside sporangium by meiosis.
- Spores are Minute and very lite, Haploid(n)
- Spore germinates to form Prothallus or Gametophyte (May be Independent or saprophytic).
- It is monoecious.
- Male sex organ is called antheridium (Globular) which produce multi cillated sperms (n).
- Female sex organ is Archegonium (flask shaped) produce Egg (n).
- Water is necessary for fertilization.
- Fertilization result in Zygote (2n) which produces Embryo.
- Embryo divides repeatedly to form new sporophyte.
- The life cycle is Diplo Haplontic Type.
.JPG "Thallus") |
| Thallus |
- Apospory: development of Diploid gametophyte from Vegetative part of sporophyte not from spore.
- Apogamy: Development of Haploid Sporophyte from gametophyte with out fusion of gametes.
- Seed habitat :In some advance pteridophytes, heterospory and seed habitat can be seen , which is believed to be the evolution of seed plants.
Classification:
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| Pteridophyta-classification |
- Homosporous - Protostele, Club moss - Homosporous, Horse tail -Homo/Heterosporous
- eg- Psilotum -
Homo/Heterosporous (Silaginella) - Equisetum - Marselia, Pteris
Economic importance :
-
Pteridophytes are used in the horticulture.
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The different species of Selaginella are grown as the garden plants.
-
Some of the
ferns are used in handicrafts; petioles
of certain ferns are used for making basketry and bracelets.
-
Pteridium leaves
are used for making the green dye.
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Club mosses are used
as a dry industrial lubricant.
The spores are also used as flash powder in photography
also as finger print powder in forensic investigation.
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Some pteridophytes are eaten as food.
-
Since Azolla leaves
contains symbiotic cyanobacteria that
are able to convert atmospheric nitrogen
to nitrate. which is used as a bio fertilizer
Dryopteris: (Fern)
Systematic Position:
- Kng- Plantae
- Div- Pteridophyta
- Sub Div- Pteropsida
- Cls- Filicinae
- Ord- Filicales
- Fam- Polypodiaceae
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Genus- Dryopteris
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| Fern |
General Character:
· World wide distributed, more than 250 sp. ,
· In India 41 species found.
· Grow in moist, wet, cool and shady places.
Commonly found in tropical and sub tropical area.· Main plant body is Sporophytic (2n).
Can differentiate in to Root, stem and leaf. |
| Droypteris |
· Root- Primary root short lived and replaced by Adventitious root.
· Black, thin, branched, help in anchorage and absorption.
· Stem-it is Under ground Rhizome, short (up to 15cm), dark brown, covered by brown scale (Ramenta), grow by single apical cell.
· Leaves- called Fronds, Magephyllus, Large, Green, Feather like, compound.
· Can grow up to 1 m. long.
· Young leaf show Circinate ptyxis (Spring like coiled)
· The long Rachis bears leaflets or pinnae.
· Leaf may contain sporangia in side Sori, thus the leaf called as Sporophyll.
Reproduction:
· Vegetative Reproduction: mostly by adventitious buds and fragmentation of Rhizome.
· Asexual Reproduction: mostly by spore.
Sporophylls contain Sori filled with group of sporangia. Sori covered by a protective layer called Indusium. Sporangia are Biconvex lens like capsule, with stalk. Capsule contain Spore mother cell, which undergo meiosis to produce spore(n). Spores are homosporous in nature. After maturity, the stomium part of capsule jacket break and Annulus part start spore dehiscence.
· On falling at suitable substratum spore germinate.
It produces monoecious prothallus or Gametophyte. |
| Life-cycle |
Gametophyte:
· Here sexual reproduction occurs.
· Gametophyte is flat, green, non-vascular, heart shaped, contain unicellular rhizoid. 5- 13 mm in diameter. It is short lived and bears sex organs.
· Antheridia- male sex organ, globular, without stalk (sessile), dome shaped, present at lower side with rhizoid. It contain about 48 androcytes, which will form coiled, multi ciliated antherozoid (n).
· Archegonium: Female sex organ, flask shape, present at upper side, contain neck and venter. Venter contain Egg (n) .
· Water is necessary for fertilization.
· When egg matures, spermatozoids are released to water. They swim to the egg by chemotactic attraction. Only one antherozoid will fuse with egg to form a Zygote(2n).
· Zygote is the 1st cell of Sporophytic Generation.
· Zygote divide and re divide to form embryo, which further divide to form new sporophyte.
Here the life cycle is Diplo- Haplontic alternation of Generation.Want to know about Bryophyte, Click the Link below:
Want to know about Kingdom of Plantae Algae , Click the Link below:
https://uksirnotes.blogspot.com/2022/09/Kingdom-Plantae-Algae-Spirogyra-uksir.html
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