Plant Reproduction: Mechanisms and Development

• Lesson 3 is on plant reproduction
• The focus question is: How do plants reproduce?

Objectives

• Define vegetative reproduction
• List the advantages and disadvantages of vegetative reproduction
• Identify flower parts and their functions using diagrams
• Describe pollination mechanisms, including wind and animals
• Compare/contrast seed and fruit development in angiosperms, but only focusing from where they originated
• List three ways of seed dispersal with examples
• Summarize the seed germination process in steps, including:
  • Absorption of water
  • Activation of enzymes
  • Growth of radicle
  • Emergence of the shoot
  • Development of seedling structures
• Lab 13 requires a lab report and involves comparing flower structures

Vegetative Reproduction

• Asexual reproduction where a new plant grows from parts of the old one
• Results in a clone of the original plant
• Advantages include:
  • Faster reproduction
  • Uniform offspring
  • The ability to produce fruit without seeds

Advantages of Vegetative Propagation

• It's a relatively quick way to produce new plants
• Good traits from the parent are passed to offspring
• No external factors or other plants are necessary for reproduction

Disadvantages of Vegetative Propagation

• Overcrowding can cause competition for resources
• Diseases from parent plants can easily transmit to offspring
• No new features in offspring can adapt to environmental changes
• Undesirable traits pass on to offspring

Flower Structure and Organs

• Flowers have organs for protection, support, and reproduction
• Flowers generally have four organs:
  • Sepals
  • Petals
  • Pistils
  • Stamens
• Sepals protect the flower bud and can resemble small leaves or petals
• Petals are colorful, attract pollinators, and provide a landing platform
• Stamens are the male reproductive structure
• The pistil is the female reproductive structure

Animal Pollination

• Flowers are brightly colored or strongly scented to attract pollinators

Wind Pollination

• Flowers lack showy or fragrant flowers
• Produce large amounts of lightweight pollen

Seed and Fruit Development in Flowering Plants (Angiosperms)

• The zygote divides to become an embryo
• Endosperm tissue provides nutrients to the growing embryo
• The endosperm is mostly absorbed into cotyledons of eudicots
• While the endosperm accounts for a large volume of monocot seeds
• The outer ovule layers harden and form a protective tissue called the seed coat as the endosperm matures
• A plant's ovary can contain one or many ovules
• As the ovule develops into a seed, changes in the ovary cause it to develop into a fruit

Seed Dispersal

• Fruits aid in dispersing seeds away from the parent plant
• This reduces competition and increases survival chances
• Some seeds pass unharmed through animal digestive tracts before being deposited
• Some seeds have structural modifications and enable transport by water, animals, or wind

Seed Germination

• When the embryo in a seed starts to grow it is called germination
• Germination begins when a seed absorbs water
• The radicle is the first part of the embryo to appear outside of the seed
• The hypocotyl is the first part of the seed to appear above ground
• Seeds may enter dormancy, a state of little to no growth to increase survival in harsh conditions at the end of the growing season
• The length of dormancy varies between species

Explore plant reproduction, covering vegetative reproduction, flower structures, and pollination. Compare seed and fruit development in angiosperms, focusing on their origins. Further investigate seed dispersal methods and the seed germination process. Includes lab activity to study flower structures.