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Seedless Plants
Early Plant Life
Biology Textbooks Boundless Biology Seedless Plants Early Plant Life
Biology Textbooks Boundless Biology Seedless Plants
Biology Textbooks Boundless Biology
Biology Textbooks
Biology
Concept Version 6
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Early Plant Life

A diverse array of seedless plants still populate and thrive in the world today, particularly in moist environments.

Learning Objective

  • Describe the pervasiveness of seedless plants during the history of the kingdom Plantae


Key Points

    • Non-vascular seedless plants, or bryophytes, are the group of plants that are the closest extant relative of early terrestrial plants.
    • The vast majority of terrestrial plants today are seed plants, which tend to be better adapted to the arid land environment.
    • Seedless plants are classified into three main catagories: green algae, seedless non-vascular plants, and seedless vascular plants.

Terms

  • vascular plant

    any plant possessing vascular tissue (xylem and phloem), including ferns, conifers, and flowering plants

  • bryophyte

    seedless, nonvascular plants that are the closest extant relative of early terrestrial plants


Full Text

Introduction to Early Plant Life

An incredible variety of seedless plants populates the terrestrial landscape. Mosses may grow on a tree trunk and horsetails may display their jointed stems and spindly leaves across the forest floor . Today, however, seedless plants represent only a small fraction of the plants in our environment. The kingdom Plantae constitutes a large and varied group of organisms with more than 300,000 species of cataloged plants. Of these, more than 260,000 are seed plants. However, three hundred million years ago, seedless plants dominated the landscape and grew in the enormous swampy forests of the Carboniferous period. Their decomposition created large deposits of coal that we mine today.

Horsetails are seedless plants

Seedless plants, like these horsetails (Equisetum sp.), thrive in damp, shaded environments under a tree canopy where dryness is rare.

Current evolutionary thought holds that all plants, green algae as well as land dwellers, are monophyletic; that is, they are descendants of a single common ancestor. The evolutionary transition from water to land imposed severe constraints on plants. They had to develop strategies: to avoid drying out, to disperse reproductive cells in air, for structural support, and for capturing and filtering sunlight. While seed plants developed adaptations that allowed them to populate even the most arid habitats on Earth, full independence from water did not happen in all plants. Most seedless plants still require a moist environment.

Seedless plants are classified into three main categories: green algae, seedless non-vascular plants, and seedless vascular plants. Seedless non-vascular plants (bryophytes), such as mosses, are the group of plants that are the closest extant relative of early terrestrial plants. Seedless vascular plants include horsetails and ferns.

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