Correct Answer - Option 2 : Isoetes
Concept-
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Plants are divided into five groups- Thallophytes, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms.
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Pteridophytes are the first terrestrial plants to acquire vascular tissues – xylem and phloem.
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Pteridophytes are also called vascular crypto games.
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Pteridophytes are used for medicinal purposes.
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Pteridophytes are not completely differentiated into root, stem, and leaves.
- Pteridophytes are divided into 4 classes-
- (1) Psilopsida (2) Lycopsida (3) Sphenopsida (4) Pteropsida
Explanation-
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Secondary growth results from cell division in the lateral meristems.
- Due to secondary growth, the stems and roots become thicken.
- Fascicular vascular cambium and cork cambium are examples of secondary growth.
Thereby secondary growth is present in Isoetes.
Note- Secondary growth is absent in pteridophytes but exceptionally present in isoetes.
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Psilopsida
- Most vascular plants.
- Examples are Psilotum.
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Lycopsida
- Club mosses are placed here.
- Examples are lycopodium.
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Sphenopsida
- Horsetails are included here.
- Examples are equisetum.
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Pteropsida
- They are commonly called ferns.
- Examples are marsilea and pteris.
