Transcript Ch.36 Plant Form - OCC

Plant Form
Chapter 36
The World of Plants
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Video Clip
Parts of a Flowering Plant
Transpiration
Transpiration in Plants
Monitoring Water in Plants
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Plant Body Organization
A vascular plant consists of:
1. Root system, which is underground
-Anchors the plant, and is
used to absorb water and minerals
2. Shoot system, which is above ground
-Consists of supporting stems,
photosynthetic leaves and
reproductive flowers
Each has an apex that extends growth
Roots, shoots and leaves contain three basic
tissue systems:
-Dermal tissue – For protection (Wax and bark)
-Ground tissue – For storage, photosynthesis
and secretion
-Vascular tissue – For conduction
-Xylem – Water and dissolved minerals
-Phloem – Nutrient-containing solution
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Plant Cells
Plant cell walls consist of cellulose
-Primary cell wall
-Found in all cells
-Cellulose fibers parallel to microtubules
-Secondary cell wall
-Found in some cells
-Additional layers of cellulose and lignin
-Increase mechanical strength of wall
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Plant Stem Cells
Meristems are clumps
of small cells with dense
cytoplasm and large nuclei
They act as stem
cells do in animals
-One cell divides producing
a differentiating cell and
another that remains
meristematic
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The Primary Plant Body
Apical meristems are located at the tips of stems and roots
-Give rise to primary tissues which are collectively called the
primary plant body
-Three primary meristems (that come from apical meristem)
Epidermis,1o vascular tissue, Ground tissue
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Secondary Plant Body (increases girth)
Lateral meristems are found in
plants that exhibit secondary
growth
-Give rise to secondary
tissues which are collectively
called the secondary plant
body
-Woody plants have two types
-Cork cambium  Outer
bark
-Vascular cambium 
2o vascular tissue
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Plant Tissues
As mentioned earlier, plants contain three
main types of tissue
-Dermal
-Ground
-Vascular
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Dermal Tissue
*Forms the epidermis, which is usually one cell
layer thick & is outer protective covering
*Covered with a fatty cutin layer constituting the
cuticle (prevents water loss)
*Contains special cells, including guard cells,
trichomes and root hairs
Guard cells are paired sausage-shaped cells
-Flank a stoma, which is the passageway for oxygen and
carbon dioxide...and is the epidermal opening between 2
guard cells
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Dermal Special Cells Continued
Trichomes are cellular or multicellular hairlike
outgrowths of the epidermis
-Keep leaf surfaces cool and reduce evaporation
by covering stomatal openings
-Some are glandular,
secreting substances
that deter herbivory
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Dermal Special Cells Continued
Roots hairs are tubular extensions of individual
epidermal cells in growing roots
-Greatly increase the
root’s surface area
and efficiency of
absorption...of water
and minerals
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Ground Tissue
A tissue that functions in food, water storage,
photosynthesis and secretion...Consist of 3 types of
cells
Collenchyma cells - support for
organs, bend but don’t break
Parenchyma cells - most common
plant cell
-storage,photosynthesis,secretion
-chloroplasts-chlorenchyma
Sclerenchyma cells - tough
thick walls...usually have
Secondary cell walls with
lignin (polymer seen 12
in
wood)
Vascular Tissue
Xylem
-Constitutes the main
water-and mineral-conducting
tissue...
Water goes in a stream from roots
to shoots and out of the leaves
via transpiration
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Vascular Tissue
Xylem
-Also conducts inorganic ions such as
nitrates, and supports the plant body
-Typically includes parenchyma cells
-Function in lateral conduction and
food storage
Note: The diffusion of water vapor from a
plant is termed transpiration
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Vascular Tissue
Phloem
-Constitutes the main food-conducting tissue in
vascular plants
-Contains an elongated living cell with no nuclei
called sieve tube members
Phloem transports
sucrose, hormones, and amino acids
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Roots
Root cap
-Contains types of cells that are
formed continuously by the root
apical meristem
Zone of elongation
-Roots lengthen because cells become
several times longer than wide
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Modified Roots
Prop roots
Aerial roots
Obtain
water from
air
Keep plant
upright
Pneumatophores
Oxygen uptake
Water storage roots
Weigh over 60 pounds
Buttress roots
Stability
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Stems
Leaves may be arranged in one of three ways
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External Stem Structure
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External Stem Structure
Node = Point of attachment of leaf to stem
Internode = Area of stem between two nodes
Blade = Flattened part of leaf
Petiole = Stalk of leaf
Axil = Angle between petiole/blade and stem
Axillary bud = Develops into branches with
leaves or may form flowers
Terminal bud = Extends the shoot system
during the growing season
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Internal Stem Structure
Vascular tissue arrangement
is directly related to the stem’s ability for
secondary growth
-In eudicots, a vascular
cambium develops between
the primary xylem and phloem
-In monocots, there is no
vascular cambium
-Therefore, no secondary growth
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Aging a Tree
Scots Pine ( Pinus sylvestris ) x3 .Transverse section represents 30 years of even growth. Note
that the summerwood (White)and spring wood (green)have different relative thickness' depending
upon weather conditions that year. Note excess production of resin which
bleeds into the ring structure as seen above right side.
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Bulbous
Underground
stem with
fleshy leaves
Swollen tip
of rhizome
Modified
Stems
Underground
Grow along
ground
stems
Used for
climbing
Resemble
leaves
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Leaves
Leaves are the main site of photosynthesis -They are
determinate structures whose growth stops at maturity
A leaf-blade has veins which consist of xylem and phloem
-Monocot leaves
have parallel
veins
-Eudicot leaves have
netted or reticulate
veins
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Leaves
Simple – undivided blades
Pinnate - paired
leaflets
Palmate - center axis
of leaflets
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Basic Leaf Histology
Epidermis has a waxy cuticle
-The lower epidermis contains numerous
mouth-shaped stomata flanked by guard cells
The mesophyll is the tissue between
the upper and lower epidermis
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Evergreen vs. Deciduous
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Male vs Female Cones
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What is Pollen?
Catkins
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