STRUCTURE OF A FLOWER•Flowers are reproductive organs

that are composed of four kinds of

specialized leaves:

1. Petals

2. Sepals

3. Stamens

4. Carpels (also called Pistils)

Petals – Brightly colored structure

just inside the sepals; attracts insects

and other pollinators to a flower.

Sepals – Outermost circle of flower

parts that encloses a bud before it

opens and protects the flower while

it is developing.

Pistil (also called carpel) –Female part of a plant;

Innermost part of a flower

that produces the female

gametophyte.•Stigma- Sticky portion

located at the top of the style

where pollen frequently

lands

•Broad base forms an ovary,

which contains one or more

ovules (contains eggs inside)

•The diameter of the carpel

narrows into a stalk called a

style.

PISTIL OR CARPAL

STIGMA

STYLE

Complete Flower – Has all

four organs

Incomplete Flower – Lacks

one or more organs

Pollination – Transfer of pollen from the stamen to

the pistil.

Methods of Pollination:

1. Wind

2. Animals (most are

pollinated by animals)

Pollination Adaptations That Attract Animals:

1. Nectar

2. Petal Color

3. Scent

POLLINATION

TYPES OF POLLINATION

Self-Pollination – Stigma receives pollen from the

same plant.

Cross-Pollination – Pollen

from one plant is carried to the

stigma of another plant.

-Must be same type of plant.

-Allows for exchange of

genetic material

Reproduction in Flowers

Similar to Gymnosperms Since:

1. Both produce seeds

2. Gametophytes are within the body of the

sporophyte.

FERTILIZATION IN FLOWERS1. Pollen grain lands on the stigma.

2. The pollen tube cell grows a tube to the ovary.

3. The two sperm cells move through the tube into the ovule.

•One sperm joins with the egg in the ovule.

•The other joins with the central cell (2N) to form the endosperm

(3N)

•The process is called double fertilization.

•Double Fertilization - Fertilization in angiosperms, in

which two distinct fertilization events take place between

the male and female gametophyte.

SEED FORMATION

1. After fertilization occurs, the flower dies and the

seed develops.

2. Ovule becomes the seed coat which protects the

embryo.

3. The zygote divides becoming the embryo.

4. The 3N central cell develops into the endosperm

which is food-storage tissue.

FRUITS

The ovary develops into the

fruit, which can be dry or

fleshy.

Fruits protect the seeds and

aid in dispersal.

Dry Fleshy

Examples: Nuts and Grains Examples: Oranges, Peaches,

Tomatoes, Squash

SEED

GERMINATION

Seeds can remain dormant

until conditions are right for

development and growth.

-Water, oxygen, and

favorable temperatures

are usually needed.

Germination – Early plant

stage of a plant embryo.

- Germination is the development

of the seed into a new plant.

During growth, the roots appears first,

then the stem, and finally the leaves.

GROWTH AND DEVELOPMENTPlants respond to stimuli from the environment. This

process is called TROPISM.

Positive Tropism - Growth towards the stimulus.

Negative Tropism – Growth away from the stimulus

Phototropism – Growth towards

light

Gravitropism – Response to gravity

Thigmotropism- response to touch

Phototropism- causes a plant to

grow towards a light source.

The experiment to the left

shows the importance of

apical meristems to the

growth of stems towards a

light source.

Geotropism (Gravitropism)-

causes the shoot of a germinating

seed to grow out of the soil (against

gravity). It also causes the roots of a

plant to grow with the force of

gravity and into the soil.

Gravitropism

and

phototropism

work

together, and

are controlled

by the

hormone

auxin.

Thigmotropism- a plant can be

effected by touch in many ways:

• Plants touched regularly could have

stunted growth

• Vines and climbing plants form

structures that attach themselves to

things they touch.

Ex. Some climbing plants have long,

twisting leaf tips, or petioles that wrap

tightly around small objects.

Ex. Other plants have extra growths

called tendrils that emerge near the

base of the leaf and wrap tightly

around any object.

Tendrils

http://www.youtube.com/watch?v=9bRtll-Ha0o

http://www.youtube.com/watch?v=dTljaIVseTchttp://player.discoveryeducation.com/index.cfm?guidAssetId=CCF5235B-94BB-42F1-

8E4B-78F82E6847BB&blnFromSearch=1&productcode=US (life venus fly)

http://www.youtube.com/w

atch?v=H9MV5CgPgIQ&f

eature=fvsr