Why pteridophytes are called highly developed non flowering plants?Give at least three reasons.
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1. Plant body is sporophytic.
2. Real stem and leaves are present.
3. Fixation of plant body is small and independent.
4. They are vascular plants.
2. Real stem and leaves are present.
3. Fixation of plant body is small and independent.
4. They are vascular plants.
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A pteridophyte is a vascular plant (with xylemand phloem) that reproduces by spores and lacks seeds. Because pteridophytes produce neither flowers nor seeds, they are also referred to as "cryptogams", meaning that their means of reproduction is hidden. The pteridophytes include the ferns, horsetails, and the lycophytes (clubmosses,spikemosses, and quillworts). These are not amonophyletic group because ferns and horsetails are more closely related to seed plants than to the lycophytes. Therefore, "Pteridophyta" is no longer a widely accepted taxon, although the term pteridophyte remains in common parlance, as do pteridology andpteridologist as a science and its practitioner, to indicate lycophytes and ferns as an informal grouping, such as the International Association of Pteridologists and the Pteridophyte Phylogeny Group.
DescriptionEdit
Ferns and lycophytes (pteridophytes) are free-sporing vascular plants that have a life cyclewith free-living, independent gametophyte andsporophyte phases. Their other common characteristics, include vascular plantapomorphies (e.g., vascular tissue) and land plant plesiomorphies (e.g., spore dispersal and the absence of seeds).[1] [2]
TaxonomyEdit
PhylogenyEdit
Of the pteridophytes, ferns account for nearly 90% of the extant diversity.[2] Smith et al. (2006), the first higher-level pteridophyte classification published in the molecular phylogenetic era, considered the ferns as monilophytes, as follows:[3]
Division Tracheophyta (tracheophytes) - vascular plantsSub division Euphyllophytina(euphyllophytes)Infradivision Moniliformopses(monilophytes)Infradivision Spermatophyta - seed plants, ~260,000 speciesSubdivision Lycopodiophyta(lycophytes) - less than 1% of extant vascular plants
where the monilophytes comprise about 9,000 species, including horsetails (Equisetaceae),whisk ferns (Psilotaceae), and alleusporangiate and all leptosporangiate ferns. Historically both lycophytes and monilophytes were grouped together as pteridophytes (ferns and fern allies) on the basis of being spore-bearing ("seed-free"). In Smith's molecular phylogenetic study the ferns are characterised by lateral root origin in theendodermis, usually mesarch protoxylem in shoots, a pseudoendospore, plasmodialtapetum, and sperm cells with 30-1000flagella.[3] The term "moniliform" as in Moniliformopses and monilophytes means "bead-shaped" and was introduced by Kenrick and Crane (1997)[4] as a scientific replacement for "fern" (including Equisetaceae) and became established by Pryer et al. (2004).[5] Christenhusz and Chase (2014) in their review of classification schemes provide a critique of this usage, which they discouraged as irrational. In fact the alternative name Filicopsida was already in use.[6] By comparison "lycopod" or lycophyte (club moss) means wolf-plant. The term "fern ally" included under Pteridophyta generally refers to vascular spore-bearing plants that are not ferns, including lycopods, horsetails, whisk ferns and water ferns (Marsileaceae, Salviniaceae and Ceratopteris), and even a much wider range of taxa. This is not a natural grouping but rather a convenient term for non-fern, and is also discouraged, as is eusporangiate for non-leptosporangiate ferns.[7]
However both Infradivision and Moniliformopses are also invalid names under the International Code of Botanical Nomenclature. Ferns, despite forming amonophyletic clade, are formally only considered as four classes (Psilotopsida;Equisetopsida; Marattiopsida;Polypodiopsida), 11 orders and 37 families, without assigning a higher taxonomic rank.[3]
Furthermore, within the Polypodiopsida, the largest grouping, a number of informal clades were recognised, including leptosporangiates, core leptosporangiates, polypods(Polypodiales), and eupolypods (includingEupolypods I and Eupolypods II).[3]
In 2014 Christenhusz and Chase, summarising the known knowledge at that time, treated this group as two separate unrelated taxa in a consensus classification;[7]
Lycopodiophyta (lycopods) 1 subclass, 3 orders, each with one family, 5 genera, approx. 1,300 speciesPolypodiophyta (ferns) 4 sublasses, 11 orders, 21 families, approx. 212 genera, approx. 10,535 speciesSubclass Equisetidae Warm.Subclass Ophioglossidae KlingeSubclass Marattiidae KlingeSubclass Polypodiidae Cronquist, Takht. & Zimmerm.
These subclasses correspond to Smith's four classes, with Ophioglossidae corresponding to Psilotopsida.
The two major groups previously included in Pteridophyta are phylogenetically related as follows:[7][8][9]
Tracheophyta – vascular plants
Lycopodiophyta
Euphyllophyta
Polypodiophyta– ferns
Spermatophyta – seed plants
Gymnospermae
Angiospermae– flowering
DescriptionEdit
Ferns and lycophytes (pteridophytes) are free-sporing vascular plants that have a life cyclewith free-living, independent gametophyte andsporophyte phases. Their other common characteristics, include vascular plantapomorphies (e.g., vascular tissue) and land plant plesiomorphies (e.g., spore dispersal and the absence of seeds).[1] [2]
TaxonomyEdit
PhylogenyEdit
Of the pteridophytes, ferns account for nearly 90% of the extant diversity.[2] Smith et al. (2006), the first higher-level pteridophyte classification published in the molecular phylogenetic era, considered the ferns as monilophytes, as follows:[3]
Division Tracheophyta (tracheophytes) - vascular plantsSub division Euphyllophytina(euphyllophytes)Infradivision Moniliformopses(monilophytes)Infradivision Spermatophyta - seed plants, ~260,000 speciesSubdivision Lycopodiophyta(lycophytes) - less than 1% of extant vascular plants
where the monilophytes comprise about 9,000 species, including horsetails (Equisetaceae),whisk ferns (Psilotaceae), and alleusporangiate and all leptosporangiate ferns. Historically both lycophytes and monilophytes were grouped together as pteridophytes (ferns and fern allies) on the basis of being spore-bearing ("seed-free"). In Smith's molecular phylogenetic study the ferns are characterised by lateral root origin in theendodermis, usually mesarch protoxylem in shoots, a pseudoendospore, plasmodialtapetum, and sperm cells with 30-1000flagella.[3] The term "moniliform" as in Moniliformopses and monilophytes means "bead-shaped" and was introduced by Kenrick and Crane (1997)[4] as a scientific replacement for "fern" (including Equisetaceae) and became established by Pryer et al. (2004).[5] Christenhusz and Chase (2014) in their review of classification schemes provide a critique of this usage, which they discouraged as irrational. In fact the alternative name Filicopsida was already in use.[6] By comparison "lycopod" or lycophyte (club moss) means wolf-plant. The term "fern ally" included under Pteridophyta generally refers to vascular spore-bearing plants that are not ferns, including lycopods, horsetails, whisk ferns and water ferns (Marsileaceae, Salviniaceae and Ceratopteris), and even a much wider range of taxa. This is not a natural grouping but rather a convenient term for non-fern, and is also discouraged, as is eusporangiate for non-leptosporangiate ferns.[7]
However both Infradivision and Moniliformopses are also invalid names under the International Code of Botanical Nomenclature. Ferns, despite forming amonophyletic clade, are formally only considered as four classes (Psilotopsida;Equisetopsida; Marattiopsida;Polypodiopsida), 11 orders and 37 families, without assigning a higher taxonomic rank.[3]
Furthermore, within the Polypodiopsida, the largest grouping, a number of informal clades were recognised, including leptosporangiates, core leptosporangiates, polypods(Polypodiales), and eupolypods (includingEupolypods I and Eupolypods II).[3]
In 2014 Christenhusz and Chase, summarising the known knowledge at that time, treated this group as two separate unrelated taxa in a consensus classification;[7]
Lycopodiophyta (lycopods) 1 subclass, 3 orders, each with one family, 5 genera, approx. 1,300 speciesPolypodiophyta (ferns) 4 sublasses, 11 orders, 21 families, approx. 212 genera, approx. 10,535 speciesSubclass Equisetidae Warm.Subclass Ophioglossidae KlingeSubclass Marattiidae KlingeSubclass Polypodiidae Cronquist, Takht. & Zimmerm.
These subclasses correspond to Smith's four classes, with Ophioglossidae corresponding to Psilotopsida.
The two major groups previously included in Pteridophyta are phylogenetically related as follows:[7][8][9]
Tracheophyta – vascular plants
Lycopodiophyta
Euphyllophyta
Polypodiophyta– ferns
Spermatophyta – seed plants
Gymnospermae
Angiospermae– flowering
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