Lab 7 Kingdom Plantae Primary and Secondary Growth

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Lab 7 Kingdom PlantaePrimary and Secondary
Growth

• Principles of Biology II Laboratory
• BSC 1011L
• Associate Professor Pamela L. Pannozzo

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How Do Plants Grow?

• Primary growth length-wise growth, from
  meristems
• Secondary growth width-wise growth, from
  cambium
• Gymnosperms and Dicots only, not Monocots

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Primary Growth Tissues

• Protoderm epidermis
• Procambium vascular columns
• Ground meristem fills in, pith, cortex
• Meristem area of rapidly dividing meristematic
  cells, undifferentiated
• Apical meristem at root base or shoot tip,
  causes root/stem length-wise growth

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Coleus stem l.s.
protoderm
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Monocot root l.s.--Zea
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Secondary Growth Tissues

• Lateral meristems between xylem and phloem,
  causes root/stem width-wise growth
• Periderm bark, replaces epidermis
• Vascular Cambium between secondary xylem and
  secondary phloem causes root to grow in diameter
• Cork Cambium between cortex and periderm

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Periderm
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Basswood stem c.s.
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Types of Wood

• Hardwood angiosperm dicots, tracheids and
  vessel elements
• Softwood gymnosperms, mostly tracheids, no
  vessel elements
• Heartwood xylem blocked with resins,
  non-functioning
• Sapwood xylem functioning
• Monocot wood not really wood--fibers

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Types of Wood

• Hardwood

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Types of Wood

• Softwood

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Hard wood (oak)
Soft wood (pine)
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Types of Wood

• Heartwood

• Sapwood