Plant Anatomy
Quiz 12B
Two important characteristics
of plant cells
• cell walls
• plastids
Cell Walls
• outer boundary, provide
support, made mostly of
cellulose
• Most plants are supported by
two related systems: cell walls
& turgor pressure.
Turgor Pressure
water pressure inside a
plant cell’s central vacuole;
causes the stiffness of the
plant cells
Plastids
storage center in plant cells
•Stores pigments, starch or oil.
•Examples are chloroplasts
contain the green pigment
chlorophyll which is used
in photosynthesis to
capture light energy
Chloroplasts
Plant Pigments
Chlorophyll: green
Xanthophyll: yellowish colors
Carotene: yellowish-orange colors
Anthocyanin: red, blue, and purple
tissue
a group of similar cells
working together to perform
a particular function
Our bodies have four
basic kinds of tissues
• epithelial (skin)
• muscle
• connective
• nerve
A typical plant has 3
distinct kinds of tissue
• Structural tissue
• Meristematic tissue
• Vascular tissue
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
Structural Tissue
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
Meristematic Tissue
Vascular Tissue
The plant’s 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
Vascular Tissue
Xylem: long, thick-walled hollow cells
(like staws)
Phloem: slightly thinner than xylem
and not completely hollow tubes
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 thickwalled cells called fibers.
Fibrovasular bundles: xylem and
phloem surrounded by supporting
tissues
Vascular Tissue
Vascular Tissue
Xylem
Phloem
Vascular Tissue
Vascular
Tissue
Vascular
Tissue
Sunflower
Stem
Vascular
Tissue
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
Cross Section of a Leaf
Cross Section of a Leaf
Cross Section of a Leaf
Cross Section of a Leaf
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
Kinds of Wood
• Heartwood - dead xylem
cells that are often darker
• Sapwood - xylem that
conduct water and minerals
Heartwood & Sapwood
Kinds of Wood
• Springwood - xylem cells that
develop early in the growing
season
• Summerwood - small, thickwalled xylem cells that develop
later in the growing season
Springwood & Summerwood
Kinds of Wood
• Hardwood - comes primarily from
angiosperms (oaks, maples, walnut,
cherries)
• Softwood - comes primarily from
gymnosperms (firs, pine, cedars,
spruce)
Hardwood
Softwood
Heartwood & Sapwood
bark
the outer
covering of
woody plant
parts(makes
new xylem
and phloem
cells)
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
cork
heartwood
Annual
growth
ring
sapwood
(xylem)
phloem
cork
vascular
cambium
forms a tough,
water proof
coating that
keeps harmful
organisms out
and moisture
cork cambium
a layer of
living cells just
under the
dead cork
(produces new
cork cells)