Practicing Success
Recognise the figure and find out the correct matching: |
a-Leaves, b-Stem, c-Rhizoid, d-Psilopsid a-Fronds, b-Stem, c-Rhizoid, d-Sphenopsid a Leaves, b-Frond, c-Root, d-Pteropsid a-Leaves, b-Stem, c-Root, d-Lycopsid |
a-Leaves, b-Stem, c-Root, d-Lycopsid |
The correct answer is Option (4) –a-Leaves, b-Stem, c-Root, d-Lycopsid Selaginella The Pteridophytes include horsetails and ferns. Pteridophytes are used for medicinal purposes and as soil-binders. They are also frequently grown as ornamentals. Evolutionarily, they are the first terrestrial plants to possess vascular tissues – xylem and phloem. In pteridophytes, the main plant body is a sporophyte which is differentiated into true root, stem and leaves . These organs possess well-differentiated vascular tissues. The leaves in pteridophyta are small (microphylls) as in Selaginella or large (macrophylls) as in ferns. The sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls. In some cases sporophylls may form distinct compact structures called strobili or cones (Selaginella, Equisetum).Genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous. The megaspores and microspores germinate and give rise to female and male gametophytes, respectively. The pteridophytes are further classified into four classes: Psilopsida (Psilotum); Lycopsida (Selaginella, Lycopodium), Sphenopsida (Equisetum) and Pteropsida (Dryopteris, Pteris, Adiantum) . |