Plant Structure and Growth

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Chapter 35

• Plant Structure and Growth

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Structure of Angiosperms

• Highly adaptable (more so than animals) to the
  environmental pressures they endure
• Cacti has short condensed leaves to reduce
  surface area
• Cabomba species in the water has feathery leaves,
  and broad leaves on the surface for floating

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Three Basic Organs

• Two main groups of flowering plants
• Monocots and Dicots
• Roots, Stems, and Leaves

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Root System

• Roots anchor the plant, absorb minerals and
  water, and store food
• Roots contain root hairs
• Increased surface area for absorption
• Adventitous roots
• Roots that grow above ground
• Cyprus knees
• Corn roots

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Shoot System

• Stems and Leaves
• Consist of nodes (leaf bases) and internodes
  (spaces of the stem between leaves)
• Nodes contain axillary buds
• Which may form a vegetative branch (new stem)
• Terminal bud the growing portion of the stem tip

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Shoot System Leaves

• Main photosynthetic unit of the plant
• Made up of a blade and petiole

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Plant Organ Tissues

• Three tissue types
• Dermal epidermis
• Plant covering
• Vascular transport of materials between roots
  and shoots
• See vascular slide for details
• Ground - neither dermal or vascular
• Pith and cortex
• Responsible for photosynthesis
• Storage and support

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Vascular Tissue

• Made up of Xylem and Phloem
• Xylem transports water and minerals from roots
  to shoots
• Phloem transports sugars to roots and
  nonphotosynthetic portions of plant

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Xylem
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Phloem
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Cell Types

• Each type of tissue is composed of the following
  cell types
• Parenchyma
• Thin cell walls
• Least specialized
• Perform most metabolic functions
• Do photosynthesis
• Non differentiated

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Cell Types

• Collenchyma
• Thick cell walls
• Help support young parts of plant shoot
• Strings of celery stalk
• Alive at maturity
• Sclerenchyma
• Support
• Occur in non growing regions of a plant
• Die at functional maturity
• Tracheids are sclerenchyma

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Plant Growth and Development

• Plants grow as long as they live
• Indeterminate growth
• Due to perpetually embryonic tissues called
  meristems
• Can become anything
• Apical meristems primary growth
• Lateral meristems secondary growth
• Only in woody plants

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Primary Growth of Roots
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Primary Tissues of Root
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Primary Growth of Stems
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Primary Tissue of Stems
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Tissue Organization of Leaves
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Secondary Growth of Stems

• The widening of the stem
• Common in dicots and gymnosperms
• Due to vascular cambium and cork cambium

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Secondary Growth of Stem