13.1 Succession 13.2 Asexual Reproduction 13.3 Sexual Reproduction Pages

Succession The gradual change in types of species found in an area over time.

Primary Succession Begins on bare rock Examples: after glaciers recede, volcanoes spew dust and lava or after explosions. Pioneer plants are first colonizers Lichens  mosses  small herbaceous plants  larger herbaceous plants and shrubs  trees

Secondary Succession Occurs after a disruption Examples include fire, flood, storms, plowing or digging the ground Faster transformation Bare ground  grassland  grass-shrub  pine forest  beech-maple forest

13.2 Asexual Reproduction in Plants Vegetative reproduction LeavesStemsRoots -rhizomes-suckers -corms-fragments -stolons -tuber “eyes”

pros and cons Advantages: -less energy investment -plantlets are more robust than seedlings 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 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 -Dispersed away from parent plant -seed dormancy

Gymnosperms Male cones produce microspores that develop into pollen grains Female cones produce megaspores that develop into egg-producing female 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: stamenFemale: carpel

Parts Male: stamen anther –pollen grains filament- stalk Female: carpelstyle- sticky top stigma- stalk ovary- contains ovules

Monocot vs Eudicot flowers Monocot flowers- petals in 3’s For example: tulip, lilly Eudicot flowers – petals in 4’s or 5’s or more For example: rose

Pollination Animal or wind Cross-pollination between plants Self-pollination between flowers Pollen lands on stigma Pollen tube grows down to ovary 2 haploid sperm: one fertilizes ovule to make a 2n seed, and one fertilizes an diploid polar nuclei that becomes a 3n endosperm