Plant Anatomy

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Plant Anatomy

• Quiz 12B

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Two important characteristics of plant cells

• cell walls
• plastids

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Cell Walls

• outer boundary, provide support, made mostly of
  cellulose
• Most plants are supported by two related
  systems cell walls turgor pressure.

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Turgor Pressure
water pressure inside a plant cells central
vacuole causes the stiffness of the plant cells
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Plastids
storage center in plant cells

• Stores pigments, starch or oil.
• Examples are chloroplasts

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Chloroplasts
contain the green pigment chlorophyll which is
used in photosynthesis to capture light energy
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Plant Pigments
Chlorophyll green Xanthophyll yellowish
colors Carotene yellowish-orange
colors Anthocyanin red, blue, and purple
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tissue
a group of similar cells working together to
perform a particular function
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Our bodies have four basic kinds of tissues

• epithelial (skin)
• muscle
• connective
• nerve

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A typical plant has 3 distinct kinds of tissue

• Structural tissue
• Meristematic tissue
• Vascular tissue

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Structural Tissue
Most of the body, or structure, of the plant is
structural tissue. Produce food, store food,
cover, support, and protect plant
Examples epidermis, parenchyma, mesophyll,
collenchyma, cork, sclerenchyma
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Meristematic Tissue
Found in growing areas (buds, tips of roots and
stems) Purpose the growth and repair of plants
and plant parts (where mitosis is occurring)
Examples apical lateral meristems vascular
cambium, cork cambium, pericycle
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Vascular Tissue
The plants sap-conducting tissues Two types
xylem phloem
Xylem transports water and dissolved minerals
(one kind of sap) upward (long, thick-walled
cells)
Phloem transports food manufactured in the
leaves (the other kind of sap) downward
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Vascular Tissue
Xylem long, thick-walled hollow cells (like
staws)
Phloem slightly thinner than xylem and not
completely hollow tubes
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Vascular Tissue
In leaves and in non-woody plants, the xylem and
phloem are usually arranged in vascular bundles
(veins). Vascular bundles are often supported by
thick-walled cells called fibers. Fibrovasular
bundles xylem and phloem surrounded by
supporting tissues
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Vascular Tissue
Xylem
Phloem
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Vascular Tissue
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Vascular Tissue
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Vascular TissueSunflowerStem
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Vascular Tissue
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Epidermis
The outer most tissue of most leaves, young
roots, and young stems is the epidermis. Top and
Bottom layer - epidermis (one cell thick) lack
chlorophyll and serves as protection. Often
epidermal cells secrete a waxy substances that
form a cuticle (a noncellular protective covering
of leaves) give a leaf a shiny appearance
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Cross Section of a Leaf
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Cross Section of a Leaf
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Cross Section of a Leaf
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Cross Section of a Leaf
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wood

• a collection of layers of xylem that have built
  up over several years

The oldest layer of xylem is at the center of the
woody plant part newest layer is the outermost
layer
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Kinds of Wood

• Heartwood - dead xylem cells that are often
  darker
• Sapwood - xylem that conduct water and minerals

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Kinds of Wood

• Springwood - xylem cells that develop early in
  the growing season
• Summerwood - small, thick-walled xylem cells
  that develop later in the growing season

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Kinds of Wood

• Hardwood - comes primarily from angiosperms
  (oaks, maples, walnut, cherries)
• Softwood - comes primarily from gymnosperms
  (firs, pine, cedars, spruce)

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Heartwood Sapwood
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bark
the outer covering of woody plant parts(makes new
xylem and phloem cells)
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cork
(the outer layer of bark) tough, thick-walled
cells forming the outer layer of bark in woody
plant stems made of dead, thick-cell walls
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cork
heartwood
forms a tough, water proof coating that keeps
harmful organisms out and moisture
Annual growth ring
sapwood(xylem)
phloem
cork
vascular cambium
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cork cambium
a layer of living cells just under the dead cork
(produces new cork cells)