Transcript flowering plants.

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Type 2: Angiosperms
largest phylum in the plant kingdom
• Aka: flowering plants.
Unique adaptations allow for dominating today’s
world.
• Flowers allow for efficient pollination.
– animals feed on pollen or nectar
– pollen is spread from plant to plant in process
• Fruit allows for efficient seed dispersal.
– Fruit is flower’s ripened ovary
– Surrounds and protects seed(s)
– Inside the seed is a plant embryo and endosperm
(food for the embryo)
– Many forms, but each function in seed dispersal
Fruit seeds in fox droppings
Botanists classify flowering plants into two
groups based on seed type.
• Based on the number of cotyledons, which is an embryonic “seed
leaf” (1st sprout)
• Monocots have a single seed leaf.
– leaf veins usually parallel
– flower parts usually in multiples of 3
– bundles of vascular tissue scattered in stem
• Dicots have two seed leaves.
– leaf veins usually netlike
– flower parts usually in multiples of 4 or 5
– bundles of vascular tissue in rings in stem
Monocots vs. Dicots
Flowering plants are also categorized by stem
type and lifespan.
• Stem type can be woody or herbaceous.
– Wood is a fibrous
material made up of
dead cells.
– Wood has high
concentrations of
lignin and cellulose.
– Woody stems
are stiff.
– Herbaceous plants do not
produce wood.
Oak
Iris
• There are three types of plant life spans.
– Annuals mature from seed,
flower, and die in one year.
– Biennials take two years
to compete life cycle.
– Perennials live more than
two years.
Wheat
Foxglove
Big bluestem
Flowers
• Reproductive structure
of flowering plants
• Sepals
– outer ring of leaves
– protection
• Petals
– Inner ring of leaves
– Brightly colored to
attract pollinators
• Open petals & sepals
reveal male and female
structures
Flowers
• Female Carpel
– Inner most part
– Ovary: within the
base (female
gametophyte)
– Style: long stalk
– Stigma: sticky tip,
collects pollen
• Male Stamen
– Surrounds carpel
– Filaments: long
stalks
– Anther: produces
pollen (male
gametophyte)
Pollination: when pollen grains land on
stigma
• Wind pollinated flowers- small flowers and large
amounts of pollen.
• Animal pollinated flowers- larger flowers and
less pollen (more efficient).
Fertilization takes place within the flower.
Male gametophytes, or pollen grains, are produced in the anthers.
– male spores produced in
anthers by meiosis
– each spore divides by
mitosis to form two
haploid cells
– these two cells form a
single pollen grain
pollen grain
stamen
anther
1. Pollen stick to animal or released into wind
•Animal finds a new flower to feed on
2. Pollination occurs (pollen lands on stigma)
3. Remember: Each pollen grain has to haploid cells
•1 haploid cell forms a pollen tube
•1 haploid cell divides to form 2 sperm, which slide down the pollen
tube to the ovule.
4. Flowering plants go through the process of double
fertilization.
female
gametophyte
egg
Double
Fertilization
sperm
polar nuclei
ovule
1 sperm fuse with the polar nuclei = triploid (3n) endosperm
1 sperm fuse with the egg = zygote
endosperm
5. Each ovule becomes a seed.
seed coat
Endosperm provides food
supply for embryo
embryo
6. The surrounding ovary grows into a fruit.
7. Flower dries up and fruit falls to ground.
8. Animals eat fruit….seeds come out the other end…
9. Seeds get dispersed
10. Seed germinates,(sporophyte) and the cycle starts over
ground
22.2 Flower Life Cycle
Plant Life Cycle Comparisons
Plant type
Sporophyte
Gametophyte
Dominant?
Moss
Stalk with cup (capsule) at
tip, which is where spores
are produced.
More familiar, carpet-like plant
that produces specialized
gametes
GAMETOPHYTE
Fern
More familiar, leafy plant
with clusters of spore
producing sacs (sori)
Haploid plant body (prothallus)
is size of a finger nail,
produces both male and
female parts
SPOROPHYTE
Conifer
(gymnosperm)
More familiar- like pine
trees, produces male and
female cones that
produce spores
Pollen grains are male
SPOROPHYTE
gametophytes sperm, female
gameotphytes are
microscopic eggs
Flower
(angiosperm)
More familiar- apple tree,
peach tree, zucchini,
berries, etc. Contain
flowers that produce male
and female spores
Pollen grains are male
gametophytes  2 haploid
cells = pollen tube + sperm,
Female gametophyte in ovule
 egg + 2 polar nuclei
SPOROPHYTE
End of the Semester!