13.1 Succession

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