Early Terrestrial Plants and Bryophytes

  • Life cycles

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  • Earlier terrestrial environments were inhospitable to plants due to the high levels of UV radiation and a lack of water.

  • The development of these structures led to the evolution of land plants

    • Structural support​
    • Protection from desiccation​
    • Protection from UV radiation​
    • Ability to take in CO2​
    • Ability to get water from the soil​
    • Ability to transport water to all parts of body​
    • Ability to get sperm to egg

  • Colonization of land by plants was an important biological event

    • Altered atmospheric and soil conditions
    • Allowed for other life forms to emerge on land
    • Allowed human civilization to develop and advance through agriculture and fossil fuels

  • Bryophytes

    • Gametophyte generation is dominant and photosynthetic
    • Diverse habitats, but mostly moist environments
    • Small
    • Lack vascular structures, but have simple water conducting cells
    • Motile sperm that needs water as a transport medium to meet a non motile egg
    • Sporophyte develops out of the gametophyte which provides nourishment and support
    • Disperses spores
    • Liverworts (hepatophyta):
    • Can be flat or leafy
    • Flat liverworts have rhizoids
    • Lack stomata but have open air chambers
    • Dioecious and homosporous
    • Very small sporophytes
    • Asexual reproduction of spores using gemma cups
    • Mosses (Bryophyta):
    • Have rhizoids
    • Only the sporophyte capsule has stomata
    • Most are dioecious and homosporous
    • Most abundant plant in arctic and Antarctic climates
    • Many species are drought resistant
    • Hornworts (Anthropocentriste):
    • Dominant sporophyte generation
    • Sporophytes have stomata and are photosynthetic
    • May be among the first land plants