The Structures of Seed Plants

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The Structures of Seed Plants

• Chapter 4 Section 4A

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Plant Systems

• Root system is made up of roots.
• The shoot system is made up of stems and leaves.
• Both systems are dependent on each other.
• The two vascular systems of a plant are
  connected.
• Xylem transports water and minerals
• Phloem transports sugar molecules.

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The Root of the Matter

• Root Functions
• Supply the plant with water and dissolved
  minerals that have been absorbed from the soil
  through the xylem.
• Support and anchor the plant.
• Store surplus food which has been made during
  photosynthesis

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Root Structure

• The outmost surface of a root is called the
  epidermis.
• Small extensions out from the root are called
  root hairs which increase the surface area for
  water and mineral absorption.
• Root caps protect the tip of the root and produce
  a slimy substance which makes it easier for the
  root to travel through the soil.

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Root Types

• Taproot
• One main root which grows downward
• Usually obtain water located deep underground.
• Dicots and gymnosperms have taproots.

• Fibrous Root
• Several roots of the same size that spread out
  from the base of the stem.
• Obtain water that is close to the surface.
• Monocots have fibrous roots.

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Whats the Holdup?

• Stem Functions
• Support the plant body (leaves and flowers).
• Transport materials between the root system and
  shoot system.
• Store materials such as water.

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Stem Structures

• Herbaceous Stems
• Soft, thin, flexible
• Some plants within this group live only one or
  two years.
• Wildflowers and many vegetable crops.

• Woody Stems
• Rigid
• Growing period followed by a dormant period
  producing a series of rings.
• Trees and shrubs

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Section Review

• What are three functions of roots?
• What are three functions of stems?
• Suppose the cross section of a tree reveals 12
  light-colored rings and 12 dark-colored rings.
  How many years of growth are represented?

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