Agenda

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Agenda

• Quiz
• Announcements Lab Practical Next Week, Lab
  Reports are due in 2 weeks
• Plant Anatomy Lecture (stems and roots only)
• Plant Anatomy Lab (stems and roots only)
• Next week Lab Topic 19 (leaves), Lab Topic 20,
  Practical 2

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Plants have 3 basic organs Roots Stems Leaves
Fig. 35.2 from Cambell and Reece
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• Plants Have 3 Basic Tissue Systems
• Dermal Tissue outer protective covering
• Vascular Tissue xylem and phloem, also has a
  secondary role in support
• 3) Ground Tissue makes up bulk of the plant,
  diverse functions including photosynthesis,
  storage, and support

Fig. 35.8
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Apical meristems regions of continuous cell
division, located at tips of roots and shoots,
give rise to the 3 primary meristems (protoderm,
procambium, and ground meristem)
Primary meristems accomplish primary growth
(length) Lateral meristems accomplish secondary
growth (width)
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MEMORIZE THIS
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• What organ (stem, root, leaf) am I looking
  at?
• Am I look at the external morphology or
  the internal anatomy?
• Can I identify all 3 tissue systems?
• Am I able to tell whether this is a
  monocot or a dicot?

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STEMS
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Twig Diagram
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Types of Modified Stems

• Rhizome modified stem that grows laterally
  below ground

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Types of Modified Stems

• Rhizome
• Stolon modified stem that grows laterally above
  ground

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Types of Modified Stems

• Rhizome
• Stolon
• Tuber swollen shoot tip of a rhizome

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Types of Modified Stems

• Rhizome
• Stolon
• Tuber
• Corm stem that is compressed laterally

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Types of Modified Stems

• Rhizome
• Stolon
• Tuber
• Corm
• Succulent Stem for storage

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The Apical Meristem
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Where do you find apical meristems? What do they
give rise to?
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Cross section of monocot and dicot stems.
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What is in a vascular bundle?
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How is the ground tissue different between a
monocot and dicot stem?
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Transverse, radial, and tangential sections.
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Secondary growth involves adding width to the
stem.
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1) The vascular cambium produces secondary xylem
to its interior and secondary phloem to its
exterior. Secondary xylem is what we think of as
wood. Why is wood hard and strong?
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How can you tell the difference between early
and late wood?
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2) The cork cambium produces cork. The periderm
includes the cork and cork cambium. Bark
includes everything outside the vascular cambium.
What happens to the tree when you strip the bark?
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2) The cork cambium produces cork. The periderm
includes the cork and cork cambium. Bark
includes everything outside the vascular cambium.
cork
Cork cambium
Primary phloem
What happens to the tree when you strip the bark?
Secondary phloem
Vascular Cambium
Secondary xylem
Primary xylem
pith
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What is the difference between heartwood and
sapwood?
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ROOTS
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Tap roots vs. fibrous roots vs. adventitous roots
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Root Tip
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Cross Section of a Dicot Root

• Cortex occupies most of the volume. What
  primary meristem is it from? What do you think
  the main function of the cortex cells is?

endodermis
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Cross Section of a Dicot Root

• Cortex occupies most of the volume. What
  primary meristem is it from? What do you think
  the main function of the cortex cells is?
• The inermost layer of cells in the cortex is
  called the endodermis.

endodermis
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Cross Section of a Dicot Root

• Cortex occupies most of the volume. What
  primary meristem is it from? What do you think
  the main function of the cortex cells is?
• The inermost layer of cells in the cortex is
  called the endodermis.
• The pericycle is the layer of cells just inside
  the endodermis. The pericyle surrounds the
  vascular cylinder (stele).

endodermis
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Cross Section of a Dicot Root

• Cortex occupies most of the volume. What
  primary meristem is it from? What do you think
  the main function of the cortex cells is?
• The inermost layer of cells in the cortex is
  called the endodermis.
• The pericycle is the layer of cells just inside
  the endodermis. The pericyle surrounds the
  vascular cylinder (stele).
• Roots can get woody too. This happens similarly
  to the development of wood in stems. The
  vascular cambium secretes secondary xylem and
  phloem. The cortex, endodermis, and epidermis
  eventually get sloughed off.

endodermis
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Cross Section of a Monocot Root
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How can you tell the difference between a monocot
and a dicot root?
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What is this?
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LOTS TO LOOK AT

• Twig
• Modified stems
• Slide of apical meristem
• Slides of monocot and dicot stems
• Wood cookies
• Slide of woody stem in primary growth and slide
  of older woody stem
• Types of roots
• Slide of root apical meristem
• Slides of monocot and dicot roots

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• What organ (stem, root, leaf) am I looking
  at?
• Am I look at the external morphology or
  the internal anatomy?
• Can I identify all 3 tissue systems?
• Am I able to tell whether this is a
  monocot or a dicot and how?

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NEXT WEEK

• Lab Practical, Lab topic 19 (stems), Lab topic 20