Pteridophytes

A pteridophyte is a vascular plant that disperses spores and has xylem and phloem. Pteridophytes are frequently referred to as "cryptogams," meaning that their mechanisms of reproduction are hidden since they do not produce blooms or seeds.Horsetails and ferns are examples of Pteridophytes. Pteridophytes are utilized as soil binders and for therapeutic purposes. They're also commonly used as ornamentals. They are the first terrestrial plants to have vascular tissues – xylem and phloem – according to evolution. Pteridophytes prefer chilly, damp, shady environments, yet some can thrive in sandy soil.

Pteridophytes, have a sporophyte that is divided into real roots, stems, and leaves. The vascular tissues in these organs are well-differentiated. Pteridophyta leaves can be microscopic (microphylls) like Selaginella or huge (macrophylls) like ferns. Sporophytes have sporangia that are cared for by sporophylls, which are leaf-like appendages. Sporophylls can sometimes develop unique compact structures known as strobili or cones (Selaginella, Equisetum).In spore mother cells, the sporangia produce spores by meiosis. The spores germinate to form prothallus, which isa small, multicellular, free-living, primarily photosynthetic thalloid gametophyte. These gametophytes can only thrive in chilly, wet, shaded environments. The proliferation of live pteridophytes is limited and restricted to certain geographical locations due to this specific constrained requirement and the necessity for water for fertilization. Male and female sex organs, known as antheridia and archegonia, are found in gametophytes. The transmission of antherozoids — male gametes released from antheridia – to the mouth of archegonium requires water. The zygote is formed when the male gamete fuses with the egg contained in the archegonium.The zygote then creates a multicellular, well-differentiated sporophyte, which is the pteridophyte's dominant phase. The majority of pteridophytes have homosporous plants, which means that all of their spores are of the same type (e.g. Psilotum, Lycopodium, and Equisetum). Heterosporous genera include Selaginella and Salvinia, which generate two types of spores: macro (big) and micro (small). Megaspores and microspores, respectively, germinate and produce female and male gametophytes. Female gametophytes are kept on the parent sporophytes for varying amounts of time in these plants. The female gametophytes are responsible for the development of the zygotes into newborn embryos. This occurrence is a prelude to the seed habit, which is considered a crucial evolutionary step.

Pteridophytes are divided into four groups: Psilopsida (Psilotum), Lycopsida (Selaginella, Lycopodium), Sphenopsida (Equisetum), and Pteropsida (Dryopteris, Pteris, Adiantum).

(a) Selaginella
(b) Equisetum
(c) Fern
(d) Salvinia

Figure 6