Topic #5: Pine Life Cycle

• In the pine life cycle, 3 of which degenerates and the last continues
• Archegonium - Pinus female gametophyte

  Embryo sac - Angiosperm female gametophyte
• Identify which stage does the following happen:

  Sporophyte Stage

  • Conifer Trees Are Monoecious
• Identify which stage does the following happen:

  Sporophyte Stage

  • 2n zygote forms
• Identify which stage does the following happen:

  Sporophyte Stage

  • Seed forms
• Identify which stage does the following happen:

  Sporophyte Stage

  • Seed is appressed in fertile scales
• Identify which stage does the following happen:

  Sporophyte Stage

  • Seed grows into a tree
• Identify which stage does the following happen:

  Gametophyte Stage

  • Megasporocyte becomes Haploid Megaspore to form Megagametophyte Archegonium through m-Meiosis
• Identify which stage does the following happen:

  Gametophyte Stage

  • Microsporocyte becomes haploid Microspore Pollen to form Microgametophyte through Meiosis.
• Identify which stage does the following happen:

  Gametophyte Stage

  • Fertilization occurs
• (1) Conifer trees are monoecious

  • Both Male and Female cones are present in one plant.
  • The female cones is larger than male cones
• Female cones: seed cone;

  Male cones: pollen cones
• Sporophyte stage - Diploid 2n

  Gametophyte stage - Haploid n
• (2) Megasporocyte becomes Haploid Megaspore to form Megagametophyte Archegonium through m-Meiosis

  • 3 megaspores degenerate
• (3) Microsporocyte becomes haploid Microspore Pollen to form Microgametophyte through Meiosis.

  • Microsporocyte equipped with air bladder which is for pollen dispersal towards female.
  • Pollination drop happens
• Pollination drop - secretion produced by ovule for capturing and transporting pollen to ovule.
• Pinus resinosa

  • There are 2 leaves per cluster
  • The number of leaves per cluster is an important taxonomic character for representative conifers in the Genus level
  • Female cone takes 2 years before they complete their life cycle
  • Their seed cones take too long to mature.
• Similar to Angiosperm life cycle such that Megasporocytes undergo Meiosis which produces 4 daughter cells