Overview
(Gr. pteris: kind of fern; phyton, plant) Subdivision of the plant kingdom, comprising the classes Lycopsida (club mosses), Sphenopsida (horsetails), Psilopsida (but see Psilophytales), and Pteropsida (the various families of ferns). They first enter the fossil record in the Silurian. They are flowerless plants exhibiting an alternation of two distinct and d issimilar generations. The first is a non-sexual, spore-bearing, sporophyte generation. It usually appears as a relatively large plant, with stems containing vascular tissue that conducts water and dissolved solutes through the plant, and usually bears the leaves and roots. Spores are produced in sporangia that are either attached to the leaves (as in ferns) or are on specialized scales (sporophylls) grouped into cones (as in horsetails and club mosses), or in the axils of leaves on unspecialized stems (as in some club mosses). The second is a sexual, gametophyte generat ion, in which the plants generally are relatively small, and without differentiation of stem, leaves, or roots. These plants bear male (antheridia) and female (archegonia) sex organs, together or on separate plants. When the eggs in the archegonia are fertilized by sperms from the antheridia, an embryo results; this can grow into a new sporophyte generation.
Photos
Taxonomy
The Subphylum Pteridophytina is a member of the Phylum Magnoliophyta. Here is the complete "parentage" of Pteridophytina:
- Domain: Eukaryota
Whittaker & Margulis,1978 - eukaryotes
- Kingdom: Plantae
Haeckel, 1866
- Subkingdom: Viridaeplantae
Cavalier-Smith, 1981 - Green Plants
- Phylum: Magnoliophyta
Cronquist, Takhtajan & W. Zimmermann, 1966 - Flowering Plants
- Subphylum: Pteridophytina (Eichler, 1883) Cavalier-Smith, 1998 - Pteridophytes
- Phylum: Magnoliophyta
Cronquist, Takhtajan & W. Zimmermann, 1966 - Flowering Plants
- Subkingdom: Viridaeplantae
Cavalier-Smith, 1981 - Green Plants
- Kingdom: Plantae
Haeckel, 1866
The Subphylum Pteridophytina is further organized into finer groupings including:
- Infraphylum (2): Filices · Lycophytae
- Class (3): Filicopsida · Lycopsida · Progymnospermopsida
Classes
Filicopsida
Lycopsida
Lycopodiopsida is a class of plants often loosely grouped as the , and includes the clubmosses. Lycopodiopsida traditionally included all the clubmosses, including Selaginella and Isoetes. However, subdivisions within the Division Lycopodiophyta are now considered ancient enough to warrant higher-level separation in accordance with cladistics. [more]
Progymnospermopsida
At least 27 species and subspecies belong to the Class Progymnospermopsida.
More info about the Class Progymnospermopsida may be found here.
Sources
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