Chapter 35

Introduction to Plants

Kingdom Plantae

• We will primarily be discussing the angiosperms
  • Phylum Anthophyta
• Flowers and fruits
  • Only group that doe/has these things
• Advanced traits
  • Seeds
  • Advanced vascular tissues

From seed to seed

The life of a flowering plant

• Seeds
  • reproductive structures produced by angiosperms and other seed plants
  • usually the result of sexual reproduction
  • contains embryos that develop into seedlings upon germination
  • has survival value

Alternation of Generations

• Exhibited by all plants (and plant-like organisms) that have sexual reproduction
• There is an alternation between a diploid (2N) form [sporophyte] and a haploid (1N) form [gametophyte]

Gametophyte (haploid)

• Gamete-producing plant fomr
• multicellular
• microscopic in flowering plants
  • female
    • embryo sac with egg
  • male
    • pollen grain
• grow and develop within flowers of angiosperms
• produces gametes by mitosis/cytokineses

Sporophyte (diploid)

• multicellular
• large "plant" in flowring plant
• produces haploid spores by meiosis (reduction)
  • called meiospores

The plant embryo

• Fertilization (syngamy) results in the formation of a diploid zygote, which undergoes mitosis to form an embryo (multicellular)
• the embryo is a sporophyte that lies dormant in the seed with a supply of stored food and a seed coat
• may lay dormant for long periods until conditions are favorable 

The plant body

Composed of three organ types

• stems
• leaves
• roots

Shoot system

• stem
  • produce leaves and branches and bear the reproductive structures
• leaves
  • flattened structure specialized for photosynthesis

Root system

• roots
  • Provide anchorage in the soil and foster efficient uptake of water and minerals
  • can store food

Growth

• Indeterminate growth
  • increasing in size as long as the plant is alive
• grows into a seedling and then a mature plant
• Plant growth occurs by 3 means
  • Increase in number of cells
    • cellular reproduction
      • (mitosis/cytokineses)
  • increase in cell size
    • elongation
  • increase in weight/mass

Development

• Mature plants produce reproductive structures
  • flowers
  • seeds
  • fruits
• flowers and floral buds are reproductive shoots that develop when shoot apical (tip) meristems produce flower parts instead of new tissues and leaves
• flowers are produced by determinate growth

Seed coats

• Flower tissues enclose and protect tiny male and female gametophytes
  • sperm in pollen fertilizes the egg, triggering ovules to develop into seed and flower parts to develop into fruit
• fruits enclose  seeds and function in seed dispersal
  • Angiosperms

 

Meristems

• Seedlings and mature plants produce new tissue from meristems
  • cell factories
• meristem is a region of undifferentiated cells that produce new tissue by cell division
• A dormant meristem occurs at the shoot and root of seed embryos
  • activate in seedlings
• mature plants have shoot apical meristems (SAM) and root apical meristems (RAM)

Mature sporophyte develop from seedlings

• photosynthesis powers the transformation