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A pteridophyte is a vascular plant (with xylem and phloem) that reproduces by means of spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden. They are also the ancestors of the plants we see today.
Vascular plants include the clubmosses, horsetails, ferns, gymnosperms (including conifers), and angiosperms (flowering plants). They are contrasted with nonvascular plants such as mosses and green algae. Scientific names for the vascular plants group include Tracheophyta, [11] [4]: 251 Tracheobionta [12] and Equisetopsida sensu lato.
The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers.They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients, and in having life cycles in which the branched sporophyte is the dominant phase.
Mosses are examples of non-vascular plants. Non-vascular plants are plants without a vascular system consisting of xylem and phloem. Instead, they may possess simpler tissues that have specialized functions for the internal transport of water. [citation needed] Non-vascular plants include two distantly related groups:
Equisetum (/ ˌ ɛ k w ɪ ˈ s iː t əm /; horsetail) is the only living genus in Equisetaceae, a family of vascular plants that reproduce by spores rather than seeds. [2]Equisetum is a "living fossil", the only living genus of the entire subclass Equisetidae, which for over 100 million years was much more diverse and dominated the understorey of late Paleozoic forests.
Asterotheca sp. is a vascularized, seedless fern that reproduces via spores that require the presence of water. This genus of fern lived from the Carboniferous to the Triassic and is an ancestor to all modern seed plants. The leaves of Asterotheca (and all ferns) are called fronds. [1]
Botrychium is a genus of ferns, seedless vascular plants in the family Ophioglossaceae. [1] Botrychium species are known as moonworts.They are small, with fleshy roots, and reproduce by spores shed into the air.
The horsetails and their fossil relatives have long been recognized as distinct from other seedless vascular plants, such as the ferns (Polypodiopsida). [7] Before the advent of modern molecular studies, the relationship of this group to other living and fossil plants was considered problematic. [8]