Pteridophytes
They are the land plants found in cool, moist places.
The plant body is differentiated into root, stem and leaves.
They are the first terrestrial plants to have vascular tissues- xylem and phloem. Hence they are called vascular cryptogams.
The main plant body is sporophyte which have root, stem and leaves with well differentiated vascular tissues.
The plants exhibit alternation of generation with the sporophyte being dominant phase.
The stem is underground called rhizome, it produces adventitious roots.
The size of leaves may be smaller called micorphylls as in Selaginella or larger called macrophylls as in fern.
An old leave bears sporangia, hence they are called as sporophyll. The sporangia produces spores after meiosis.
The spore germinates into multicellular, small, photosynthetic thalloid gamtophyte called prothallus.
The gametophyte bears male and female sex organs called antheridia and archegonia.
Fusion of male gamete and egg forms zygote, which develops into well differentiated sporophyte.
Some pteridophytes produce spores of similar kinds called homosporous(monosporous).
Some produces spores of different kind, smaller (microspore) and larger (megaspore), are called heterosporous.
The micro and mega spores germinates into male and female gametophytes respectively.
Classification of Pteridophytes
(i) Psilopsida: e.g. Psilotum
(ii) Lycopsida: ex: Selaginella, Lycopodium
(iii) Sphenopsida: e.g. Equisetum
(iv) Pteropsida: ex: Pteris, Adiantum
Gymnosperms
The term gymnosperms means naked seeded plants.
They were abundant during Mesozoic era especially in Jurassic period. Now there are two major groups namely cycads and conifers.
The ovules are not covered by ovary and remain exposed, both before and after fertilization. Since seeds are not enclosed in ovary or fruit they are called naked seeded plants.
All are perennials living for many years. The giant redwood tree(Sequoia) is known to be one of the tallest tree species.
They have generally tap root system. Roots of many species have fungal association called mycorrhiza and associate with nitrogen fixing cyanobacteria called corolloid roots.
The stem may be branched (Pinus) or unbranched (Cycas). Leaves may be simple or compound.
The plants are heterosporous, which means they produce two types of spores—microspores and megaspores.
The sporangia born on spirally arranged compact sporophylls are called strobili or cone.
The strobili bearing microsporophyll and micro sporangia are called male cone.
The microspores develop into gametophytic generation and the gametophyte is called pollen grains.
The cones bearing megasporophyll with ovules or megasporangia are called female cones.
Male and the female gametophytes do not have an independent free-living existence. They remain within the sporangia retained on the sporophytes.
The pollen grains are released from microsporangia, they are carried by wind and come in contact with ovule.
The pollen tube carries male gametes towards archegonia. The male gametes are discharged near archegonia, it follows fertilization. Zygote develops into embryo and ovule becomes seed.
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They are the land plants found in cool, moist places.
The plant body is differentiated into root, stem and leaves.
They are the first terrestrial plants to have vascular tissues- xylem and phloem. Hence they are called vascular cryptogams.
The main plant body is sporophyte which have root, stem and leaves with well differentiated vascular tissues.
The plants exhibit alternation of generation with the sporophyte being dominant phase.
The stem is underground called rhizome, it produces adventitious roots.
The size of leaves may be smaller called micorphylls as in Selaginella or larger called macrophylls as in fern.
An old leave bears sporangia, hence they are called as sporophyll. The sporangia produces spores after meiosis.
The spore germinates into multicellular, small, photosynthetic thalloid gamtophyte called prothallus.
The gametophyte bears male and female sex organs called antheridia and archegonia.
Fusion of male gamete and egg forms zygote, which develops into well differentiated sporophyte.
Some pteridophytes produce spores of similar kinds called homosporous(monosporous).
Some produces spores of different kind, smaller (microspore) and larger (megaspore), are called heterosporous.
The micro and mega spores germinates into male and female gametophytes respectively.
Classification of Pteridophytes
(i) Psilopsida: e.g. Psilotum
(ii) Lycopsida: ex: Selaginella, Lycopodium
(iii) Sphenopsida: e.g. Equisetum
(iv) Pteropsida: ex: Pteris, Adiantum
Gymnosperms
The term gymnosperms means naked seeded plants.
They were abundant during Mesozoic era especially in Jurassic period. Now there are two major groups namely cycads and conifers.
The ovules are not covered by ovary and remain exposed, both before and after fertilization. Since seeds are not enclosed in ovary or fruit they are called naked seeded plants.
All are perennials living for many years. The giant redwood tree(Sequoia) is known to be one of the tallest tree species.
They have generally tap root system. Roots of many species have fungal association called mycorrhiza and associate with nitrogen fixing cyanobacteria called corolloid roots.
The stem may be branched (Pinus) or unbranched (Cycas). Leaves may be simple or compound.
The plants are heterosporous, which means they produce two types of spores—microspores and megaspores.
The sporangia born on spirally arranged compact sporophylls are called strobili or cone.
The strobili bearing microsporophyll and micro sporangia are called male cone.
The microspores develop into gametophytic generation and the gametophyte is called pollen grains.
The cones bearing megasporophyll with ovules or megasporangia are called female cones.
Male and the female gametophytes do not have an independent free-living existence. They remain within the sporangia retained on the sporophytes.
The pollen grains are released from microsporangia, they are carried by wind and come in contact with ovule.
The pollen tube carries male gametes towards archegonia. The male gametes are discharged near archegonia, it follows fertilization. Zygote develops into embryo and ovule becomes seed.
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