6.PTERIDOPHYTES

Pteridophytes

Horsetails and ferns.

Medicinal purposes

Pteridophytes are used for medicinal purposes.

Soil-binders

Pteridophytes are used as soil-binders.

Ornamentals

Pteridophytes are frequently grown as ornamentals.

Vascular tissues

Pteridophytes are the first terrestrial plants to possess vascular tissues - xylem and phloem.

Cool, damp, shady places

Pteridophytes are found in cool, damp, shady places.

Gametophytic

In bryophytes, the dominant phase in the life cycle is the gametophytic plant body.

Sporophyte

In pteridophytes, the main plant body is a sporophyte.

True root, stem, and leaves

The sporophyte in pteridophytes is differentiated into true root, stem, and leaves.

Microphylls

The leaves in pteridophyta are small (microphylls).

Macrophylls

The leaves in pteridophyta are large (macrophylls) as in ferns.

Sporangia

The sporophytes bear sporangia.

Sporophylls

Sporangia are subtended by leaf-like appendages called sporophylls.

Strobili or cones

In some cases, sporophylls may form distinct compact structures called strobili or cones.

Meiosis

Sporangia produce spores by meiosis in spore mother cells.

Prothallus

• Spores germinate to give rise to inconspicuous, small but multicellular free-living,

• mostly photosynthetic thalloid gametophytes called prothallus.

Water requirement

• Prothallus requires cool, damp, shady places to grow.

• need for fertilisation

Antheridia and archegonia

Gametophytes bear male and female sex organs called antheridia and archegonia, respectively.

Zygote

Fusion of male gamete with the egg present in the archegonium results in the formation of a zygote.

Homosporous

Majority of the pteridophytes produce spores of similar kinds; such plants are called homosporous.

Heterosporous

Genera like Selaginella and Salvinia produce two kinds of spores, macro and micro spores, known as heterosporous.

Megaspores and microspores

Megaspores and microspores germinate and give rise to female and male gametophytes, respectively.

Embryo development

Female gametophytes retain the zygotes and develop young embryos within them.

Evolution

The development of the zygotes into the young embryos is a precursor to the seed habit and considered an important step in evolution.

Classification

• Pteridophytes are further classified into four classes:

  • Psilopsida (Psilotum),

  • Lycopsida (Selaginella, Lycopodium),

  • Sphenopsida (Equisetum),

  • and Pteropsida (Dryopteris, Pteris, Adiantum).

Pteridophytes

The ________ include horsetails and ferns.

Medicinal

Pteridophytes are used for ________ purposes and as soil-binders.

Vascular tissues

Evolutionarily, pteridophytes are the first terrestrial plants to possess xylem and phloem, which are types of ________.

Gametophytic

In bryophytes, the dominant phase in the lifecycle is the ________ plant body.

Sporophyte

In pteridophytes, the main plant body is a ________ which is differentiated into true root, stem, and leaves.

Microphylls

The leaves in pteridophyta are small, also known as ________, as in Selaginella.

Sporangia

The sporophytes bear ________ that are subtended by leaf-like appendages called sporophylls.

sporophylls

In some cases ______ may form distinct compact structures called strobili or cones (Selaginella, Equisetum).

strobili

In some cases sporophylls may form distinct compact structures called ______ or cones (Selaginella, Equisetum).

sporangia

The ______ produce spores by meiosis in spore mother cells.

spores

The sporangia produce ______ by meiosis in spore mother cells.

gametophytes

The spores germinate to give rise to inconspicuous, small but multicellular, free-living, mostly photosynthetic thalloid ______ called prothallus.

prothallus

These gametophytes require cool, damp, shady places to grow. Because of this specific restricted requirement and the need for water for fertilisation, the spread of living pteridophytes is limited and restricted to narrow geographical regions. The gametophytes bear male and female sex organs called antheridia and archegonia, respectively. Water is required for transfer of antherozoids – the male gametes released from the antheridia, to the mouth of ______.

Fusion

Fusion of male gamete with the egg present in the archegonium result in the formation of ______.

Zygote

Zygote thereafter produces a multicellular well-differentiated sporophyte which is the dominant phase of the pteridophytes.

Homosporous

In majority of the pteridophytes all the spores are of similar kinds; such plants are called ______.

Heterosporous

Genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as ______.

Gametophytes

The megaspores and microspores germinate and give rise to female and male ______, respectively.

Embryos

The development of the zygotes into young ______ take place within the female gametophytes.

Seed habit

______ is considered an important step in evolution, and pteridophytes are a precursor to this event.

Psilopsida

______ is a class of pteridophytes that includes Psilotum.

Lycopsida

______ is a class of pteridophytes that includes Selaginella and Lycopodium.

Sphenopsida

______ is a class of pteridophytes that includes Equisetum.

Pteropsida

______ is a class of pteridophytes that includes Dryopteris, Pteris, and Adiantum.