Seed Plants

• Do not require water for reproduction
• Evolution of seed plants:

  • 1st seed plants to appear on Earth were seed ferns
  • followed by first cone-bearing plants -> Gymnosperms
  • Flowering plants -> Angiosperms, relative newcomers to Earth
• Gymnosperms: ”naked seeds” (ex. Conifers, cycads, ginkgoes)
• Coniferophyta phylum reproduction begins with a sporophyte (2n) plant that develops and produces gametophytes (n) via meiosis.
• The male gametophyte in Coniferophyta phylum reproduction is produced in pollen cones.
• The female gametophyte in Coniferophyta phylum reproduction is produced in seed cones.
• In Coniferophyta phylum reproduction, the ovule develops two or more egg cells while the pollen grains produce sperm cells.
• In spring, pollen grains in Coniferophyta phylum reproduction are released and travel to the female seed cone via wind.
• A pollen tube forms in Coniferophyta phylum reproduction that provides access to the ovule inside the female seed cone.
• A long period of time may pass before a sperm is released from the pollen grain in Coniferophyta phylum reproduction, which then travels down the pollen tube and fertilizes the egg inside the seed cone.
• After another year or so, the zygote in Coniferophyta phylum reproduction develops into an embryo inside a hard seed.
• There may be a wing that develops on the seed in Coniferophyta phylum reproduction to help with wind dispersal.
• When the seed falls and finds a suitable site in Coniferophyta phylum reproduction, it will germinate and give rise to a new sporophyte seedling.
• Angiosperms have evolved a protective type of covering over the seeds, namely, the flower and fruit