The Parts of a Flower

1
The Parts of a Flower

• Most flowers have four parts
• sepals,
• petals,
• stamens,
• carpels.

2
The parts of a flower

• Sepals protect the bud until it opens.
• Petals attract insects.
• Stamens make pollen.
• Carpels grow into fruits which contain the seeds.

3
Stamen (male)

• Anther pollen grains grow in the anther.
• When the grains are fully grown, the anther
  splits open.

4
Pistil (female)

• Stigma
• Style
• Carpel (ovary)
• Ovules (eggs)

5
Pollination

• Flowering plants use the wind, insects, bats,
  birds and mammals to transfer pollen from the
  male (stamen) part of the flower to the female
  (stigma) part of the flower.

6
Pollination

• A flower is pollinated when a pollen grain lands
  on its stigma.
• Each carpel grows into a fruit which contains the
  seeds.

7
Fertilisation

• Pollen grains germinate on the stigma, growing
  down the style to reach an ovule.
• Fertilised ovules develop into seeds.
• The carpel enlarges to form the flesh of the
  fruit and to protect the ovary.

8
Wind pollination

• Some flowers, such as grasses, do not have
  brightly coloured petals and nectar to attract
  insects.
• They do have stamens and carpels.
• These flowers are pollinated by the wind.

9
Seed dispersal

• Seeds are dispersed in many different ways
• Wind
• Explosion
• Water
• Animals
• Birds
• Scatter

10
How birds and animals help seed dispersal

• Some seeds are hidden in the ground as a winter
  store.
• Some fruits have hooks on them and cling to fur
  or clothes.

11
How birds and animals help seed dispersal

• Birds and animals eat the fruits and excrete the
  seeds away from the parent plant.

12
Sexual Reproduction

• Calyx-the outermost and often green color.
  Individual calyx-sepals-Protects inner whorls at
  bud stage
• Corolla-next inner whorl and is often colored
  brightly, -Individuals-Petals
• Anther has 4 pollen sacs, one in each lobe.
  Pollen sacs contain the mother cells, which
  undergo meiosis. Each microspere mother cell
  produces 8 sperm cells.

13
Asexual Reproduction

• In some species, stems arch over and take root at
  their tips, forming new plants. The horizontal
  above-ground stems (called stolons) of the
  strawberry (shown here) produce new daughter
  plants at alternate nodes.
• Underground stems
• rhizomes
• bulbs
• corms and
• tubers
• are used for asexual reproduction as well as for
  food storage. Irises and day lilies, for example,
  spread rapidly by the growth of their rhizomes.

14
Asexual Reproduction

• This photo shows the leaves of the common
  ornamental plant Bryophyllum (also called
  Kalanchoë) . Mitosis at meristem along the leaf
  margins produce tiny plantlets that fall off and
  can take up an independent existence

15
Asexual Reproduction

• Some plants use their roots for asexual
  reproduction. The dandelion is a common example.
  Trees, such as the poplar or aspen, send up new
  stems from their roots. In time, an entire forest
  of trees may form all part of a clone of the
  original tree.
• Apple seeds are planted only for the root and
  stem system that grows from them. After a year's
  growth, most of the stem is removed and a twig
  (scion) taken from a mature plant of the desired
  variety is inserted in a notch in the cut stump
• Citrus trees and many other species of
  angiosperms use their seeds as a method of
  asexual reproduction a process called apomixis.
• In one form, the egg is formed with 2n
  chromosomes and develops without ever being
  fertilized.
• In another version, the cells of the ovule (2n)
  develop into an embryo instead of the fertilized
  egg.