Phylum Bryophyta

• Evoled from algae, most primitive of land plants
• no protective surface covering (loses water all the time). Don’t need to be submerged but must be wet most of the time.
• Found in swamps, marshes, near rivers, rain forests
• no true roots, leaves, or stems
• tissues are one cell thick
• lack connective tissues and water conductive tubes that are found in higher plants
• water passes cell to cell by diffusion and by surface tension (work only on short distances), almost all less than few cm tall
• life cycle involves alternation of generation (haploid gametophyte with diploid sporophyte). Some can survive dry periods, but must stop growing, flagellated sperm cells must be able to swim through water
• requires water for reproduction
• moss: haploid gametophytes growing close together are haploid gametophytes. Thin shoots “stems and leaves” do not contain water tubes therefore are not “true“ leaves and stems. Rhizoids penetrate ground to anchor itself.
• Liverworts: rarer than mosses. must be kept wet continously. gametophyte look like flat green leaves growing along the ground. when mature, produce tiny green “umbrella” that carry eggs and sperm.
• hornworts: gametophytes look like liverworts, but sporophytes differ: instead of umbrellas, they have a “horn”
• Gametophytes are the haploid (n) stage of the moss life cycle
• male gametophytes produce sperm (n) in antheridia
• female gametophytes produce eggs (n) in archegonia
• 1. fungalsperm swim through water to fertilize the eggs in the archegonium (no water, no fertilization)
  2. gametes fuse inside archegonia to produce a zygote (2n)
  3. zygote germinates to produce a sporophyte (2n)
  4. sporophyte obtains water and nutrients from the gametophyte
  5. meiosis occurs in the capsule of the sporophyte (2n) to produce spores (n)
  6. spores disperse and germinate into gametophytes (genetically different)
  7. early gametophyte growth resembles efungal hyphae and is called protonema