Download Angiosperms

First flowering plants
Angiosperm: flowering plants
vascular
heterospory
male vs. female gametophytes
flower
specialized structure for sexual
reproduction
seeds within fruit
pollen
life cycle dominated by
sporophyte stage
trees & bushes are diploid
reduced (microscopic)
gametophyte
Angiosperms
Anthophyta
More specialized xylem evolved.
Tracheids seen in gymnosperms gave rise to
vessel elements
Seeds are no longer “naked”
Xylem is reinforced by second cell wall, the
fiber (also seen in conifers)
Flower is the reproductive structure
Coevolution is seen between flowers and
animals
Identify the flower structures…
Flower variations
The Fruit
What is a fruit?
After fertilization the ovary becomes the
fruit. It protects the seeds.
Name three modifications that different
fruits have for seed dispersal.
1.
2.
3.
Sweeten and turns colorful when ripe
Have burrs that can sticks to animal’s fur
Feathery like dandelions for wind dispersal of
seeds
Angiosperm: fruiting plants
Other fruits…
Seed Dispersal
Sporophyte/Gametophytes
The life cycle of the anigosperms shows very
reduced gametophyte generations.
What is the male gametophyte?
What is the female gametopyte?
What is pollination?
Bringing pollen to the stigma.
How does self-incompatibility work?
Angiosperm Life Cycle
Double Fertilization
The pollen tube grows following
pollination and leads to double
fertilization.
What is fertilized?
Sperm + egg = zygote (2n)
Sperm + 2 polar nuclei = endosperm
(3n)
Seed Development
Endosperm develops before embryo
Endosperm provides food for
developing embryo
Embryo reaches a certain size and then
enters dormancy until germination.
Seed & Plant embryo
Seed offers…
protection for
embryo
stored nutrients
for growth of
embryo
endosperm
(3n)
cotyledons
embryo (2n)
cotyledons =
“seed” leaves,
first leaves of new
seed
coat
Germination
•
•
•
How can seed dormancy be
advantageous to a plant?
Helps with dispersal
Doesn’t leave dormancy until conditions
are good
What are some conditions for breaking
dormancy?
Desert – Only after good rainfall
Chaparral – fire
Others – coats weakened by digestive
enzymes as they pass through animal’s
digestive tract
Imbibation
Hormone release …
Radicle emerges from seed
Shoot tip breaks through the soil.
Until this point how has the embryo
received nutrients?
Endosperm(food)and radicle (water).
Review the Evolution of Alternation of
Generation in Plants
Monocots & dicots
Angiosperm are divide into 2 classes
dicots (eudicot)
2 cotyledons (seed leaves)
leaves with network of veins
woody plants, trees, shrubs, beans
monocots
1 cotyledon
leaves with parallel veins
grasses, palms, lilies
Flower Bud xs
8
nucleate
embryo
sac
Pollen grain
has 2 cells:
• Generative
cell
• Tube cell
Co-evolution: flowers &
pollinators
How a bee sees a flower…insects see
UV light = a bulls-eye to the nectar