Plant%20Growth%20and%20Reproduction

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Plant Growth and Reproduction

• Chapter 2, Lesson 7

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Seeds

• A seed is an un-developed plant with stored food
  sealed in a protective covering known as a seed
  coat.

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Germination

• The process of a seed sprouting into a new plant.

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Germination

• These are different stages in the germination
  process.

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Seedling

• A young plant that grows and develops from a
  seed.
• All seeds grow from a seed to a seedling to an
  adult plant.

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Seedling

• Most seeds swell as they take in water.
• The seed coat splits open.
• A root grows out of the seed.
• Then a tiny stem appears.

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Seedling

• One or two leaves grow from the stem, and the
  young seedling beings to grow.
• If the condition are just right, the seedling
  will mature into an adult plant.
• Then it will make seeds of its own.

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Seedling

• In some plants the time from seed to adult takes
  only days.
• A bean plant matures in just a few months.
• A peach seed takes several years to become a
  tree.

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Life Cycle of a Peach Tree
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Parts of a Seed

• In order for a seed to germinate (the process of
  a seed sprouting into a new plant) it needs.
• A seed must move from the flower to a place where
  it can sprout.
• Most seeds need water and warm temperatures to
  germinate.

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Parts of a Seed

• Once the seedling begins to grow, it needs the
  right amount of light.
• The leaves of the growing plant need light to
  make oxygen.
• A seedling also needs oxygen from the air and
  nutrients from the soil.

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Pollen

• Male sex cells are found in the pollen.
• The pollen grains are like a soft powder.

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Anther

• The pollen is produced by the anthers.

Pollen
Anther
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Pistil
The female sex cells (eggs) are found in the
pistil.
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Pollination

• The transfer of a pollen grain to the pistil.
• Plants rely on insects, birds, mammals, wind, or
  water to help with pollination.

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• This is a flower.
• The pistil is the tall green stalk.
• This illustration does not reflect the anthers.

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• A pollinator comes and deposits pollen which
  lands on the pistil.
• How does that help?
• A bee might go to one flower and get a little
  pollen on its back. If it goes to another flower
  of the same species, that pollen can land on the
  pistil.

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• Pollen grains (yellow) are located on the top of
  the pistil.
• The pollen then travels down the pollen tube
  (yellow) until it reaches the ovaries.

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• The ovary then fertilizes the egg.
• Fertilization is the joining of a female sex cell
  and a male sex cell into one cell.

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Ovary

• The ovary is a structure containing egg cells.
• It is the ovary that grows to produce the
  protective fruit.

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How Are Seeds Carried Away?

• Once a seed forms, it needs a place to grow.
• The best chance of survival is to be in its own
  space, away from the parent plant. Why?
• A parent plant may soak up water and nutrients
  the seedling needs from the soil.

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How Are Seeds Carried Away?

• Therefore, a seeds best chance of survival is
  when it is carried away, or dispersed, from the
  parent.
• Seeds disperse in many different ways.

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How Are Seeds Carried Away?

• Some plants scatter their own seeds.
• The protective, fleshy fruits explode to shoot
  their seeds away from the parent plant.
• Pea and bean plants keep their seeds in a pod.
  When the seeds are ripe and the pod has dried,
  the pod burst open and peas and beans are
  scattered.

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How Are Seeds Carried Away?

• Many seeds are carried by animals.
• The fleshy fruit may attract animals that eat the
  seeds along with the fruit.
• The seeds may fall to the ground as the animals
  eat the fruit.
• If the seeds are eaten, the animals will pass
  them out in their droppings.

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How Are Seeds Carried Away?

• Other seeds are carried by the wind or water.
• A dandelion seeds have a parachute of feathery
  hairs.
• They are light enough for the wind to carry them
  long distances.

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How Are Seeds Carried Away?

• Seeds may also become attached to humans
  clothing and shoes.

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How Are Seeds Carried Away?

• Some seeds may also hitch a ride on an animals
  fur and fall off in some new place.

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The Life Cycle of Flowering Plants
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Ferns

• Ferns are green plants which can capture energy
  from the sun through photosynthesis.
• They do not have seeds, but instead simply use
  spores to reproduce.

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Moss Plants

• Do not produce flowers.
• Do not produce seeds.
• They reproduce by creating spores.

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Spores

• A spore is a cell in a seedless plant.
• Plants such as mosses and ferns use spores to
  reproduce.
• Spores do not have sex cells.
• Each spore is produced by the parent plant.
• The parent plant sheds the spores locally.
• The spore-generating organs are frequently
  located on the undersides of leaves.

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Moss Spores

• The egg is fertilized.
• The fertilized egg grows into a thin stalk with
  a spore case on top.
• The spore case opens, the spores are released.
• Spores land on damp ground and may grow into new
  moss plants.
• The life cycle begins again.

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Fern Spores

• On a fern, spores are found on the bottom side of
  the leaf.
• As the spore case matures and ripen, millions of
  spores are released and scattered into the air.
• When carried by wind currents, a small number of
  them fall on damp surfaces and soils.
• Here they form into a small, flat, kidney-shaped
  body.

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Fern Spores

• This body gets its food by
• pushing roots into the soil.
• Eventually, this plant body
• grows male and female
• organs.
• Sperm from the male organ
• fertilizes an egg from the
• female organ.
• This produces a new plant.
• The new plant produces spores,
• and the process begins again.

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Fern Spores

• The yellow spores are unopened. The brown spores
  are opened.

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The End