13.1 Succession
Pages 588-591
Succession
• The gradual change in types of species found in an area over time.
Primary Succession
• Begins on bare rockExamples: after glaciers recede, volcanoes spew dust and lava or after explosions.Pioneer plants are first colonizers
Primary succession
• Bare rock
Primary Succession
• Lichens (fungi and algae)
Moss
Primary Succession
• Grass and wild flowers
Primary Succession
• Shrubs
Primary Succession
• trees
Primary succession
• Climax forest: Maple beech forest
Secondary Succession
• Occurs after a disruption Examples include fire, flood, storms, plowing or digging the ground• Faster transformation
Secondary Succession
• construction
Secondary succession
• Forest fire
Secondary Succession
• floods
13.2 Asexual Reproduction in Seed Plants
Pages 592-594
Vegetative reproduction
Leaves
Asexual reproduction
Stems-rhizomes-corms-stolons-tuber “eyes”
Asexual Reproduction
Roots-suckers
pros and cons
Advantages: -less energy investment-quick-plantlets are more robust thanseedlings
Disadvantages: -lack of genetic variation
Grafting
branch is attached to a stem of another plant• Branch is the scion.• Donor plant is the stock.
13.3 Sexual Reproduction in Plants
Pages 595-602
• Seed-protects and nourishes the embryo
Endosperm-specialized nutritive layer
Seeds
• Seed dispersal by wind, water, animals• Gymnosperms are naked seeds• Angiosperm seeds are contained in fruits
Benefits of Sexual reproduction
-Genetic variety-Wide dispersal-Seed dormancy
Gymnosperms
• Male cones microspores pollen grains• Female cones megaspores egg-producing
gametophytes
• Wind pollination
Fertilization
• Pollen grain lands next to ovule.• Pollen tube grows to ovule. • Haploid nucleus divides into two haploid
sperm.• One sperm fertilizes ovule• Time: 13 months
Angiosperms
Male: stamen Female: carpel
Parts
• Male: stamen anther –pollen grains filament- stalk
• Female: carpel stigma- sticky topstyle- stalkovary- contains ovules
Monocot vs Eudicot flowers
• Monocot flowers- petals in 3’sEx. tulip, lilly• Eudicot flowers – petals in 4’s or 5’s or moreEx. rose
Pollination
• Animal or wind• Cross-pollination between plants• Self-pollination between flowersPollen lands on stigmaPollen tube grows down to ovary2 haploid sperm: one fertilizes ovule to make a 2n seed, and one fertilizes a diploid polar nuclei that becomes a triploid 3n endosperm