Before the flowering plants, the landscape was dominated with plants that looked like ferns for hundreds of millions of years. Today, their massive lineage have descendants that have almost the same characteristics as their ancient ancestors. Unlike most other plants that we know of, pteridophytes don’t reproduce through seeds, these plants reproduce through spores instead.
Pteridophytes can be classified into:
- Lycopodiidae (club mosses)
- Selaginellidae (quillworts, spike mosses)
- Psilotidae: Ophioglossales (e.g. grape ferns) and Psilotales (whisk ferns).
- Equisetidae (horsetails)
- Polypodiidae (leptosporangiate ferns, the most species-rich group)
- Marattiidae (marattioid ferns)
- Pteridophytes are the first true land plants:
- It is speculated that life began in the oceans, and through millions of years of evolution, life slowly adopted on to dry land. And among the first of the plants to truly live on land were the Pteridophytes.
- They are seedless, vascular cryptogams.
- Pteridophytes are seedless and they procreate through spores. They don’t have conducting tissues for transportation of water and minerals. Instead, the water and minerals flow from the surface of the plant, cell to cell in the plant’s body. This is also one of the reasons why these plants need a constantly moist environment to survive.
- They show true alternation of generations.
- The sporophyte generation and the gametophyte generation are observed in Pteridophytes.
- Sporophyte has true roots, stem and leaves.
- Spores develop in sporangia are homosporous or heterosporous.
- Sporangium are the structures in which spores are formed. They are usually homosporous (meaning: one type of spore is produced) and are also heterosporous, (meaning: two kinds of spores are produced.)
- Sporangia are produced in groups on sporophylls.
- Leaves that bear the sporangia are termed as sporophylls.
- Young leaves of sporophyte show circinate vernation.
- The tip of the leaves tend to curl inwards to protect the vulnerable growing parts.
- Sex organs multi-cellular and jacketed.
- The male sex organs are called antheridia while the female sex organs are called archegonia.
Life Cycle of Pteridophyta
Similar to the life cycle of seed plants, the pteridophytes also involves alternation of generations in its life cycle. But the pteridophytes differ from mosses and seed plants in that both generations are independent and free-living. The sexuality of pteridophytic gametophytes can be classified as follows:
- Dioicous: the individual gametophyte is either a male producing antheridia and sperm or it could be a female producing archegonia and egg cells.
- Monoicous: every individual gametophyte may produce both antheridia and archegonia and it can function both as a male as well as a female.
- Protandrous: the antheridia matures before the archegonia.
- Protogynous: the archegonia matures before the antheridia.
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