Transcript Roots - Cloudfront.net

Chapter 23
Roots 23:2
1. Roots – anchors plant into the ground and transports
materials to the plants body
A. 2 types
1. Tap – primary root that grows long and thick.
2. Fibrous – branching, where no single root grows
longer than the rest, covers a large surface area
holding soil in place.
fibrous
adventures
primary
root
II. Roots structure and Growth
• A. 3 Tissue systems
–1. Dermal – Epidermis type
found on the outside.
–2. Vascular – Central cylinder,
xylem and Phloem.
–3. Ground – Cortex, between
dermal and vascular
B. Root system plays a large role in water and
mineral transport along with protection and
absorption.
1. Root hairs – produce large surface area in
soil through which water can enter the plant.
2. Cortex- spongy layer of ground tissue.
3. Endodermis – covers the roots vascular
system.
4. Vascular Cylinder – center of the root.
5. Root Cap – covers and protects the
apical meristem cells that grow the root in
length. It secretes a slippery substance that
lubricates the progress of the root through
the soil.
Vascular, cortex, endodermis, epidermis
III Root Function
• A. Functions
–1. Anchor
–2. Absorb water and travels up the
xylem vascular tissue to the plants
body.
–3. Absorb dissolved nutrients
such as carbohydrates from
photosynthesis are transport
throughout the plants body in the
phloem vascular tissue.
•Stems
Vascular Tissue
• Xylem – vascular tissue that transports
water and minerals up into the plants
body.
• Phloem – vascular tissue that transports
food, mainly sugar throughout the body of
the plant moving in many directions.
I.
Stems 23-3 Structure and Function
A. 3 Functions
1. Produce Leaves, branches and flowers.
2. Hold leaves up to sunlight.
3. Transport substances between root and leaves.
• B. Structure
– 1. Nodes – where leaves are attached
– 2. Internode – region between the nodes.
– 3. Buds – contains under developed tissue
that can produce new stem and leaves.
C. Monocot and Dicot Stems
• 1. Monocot stems – scattered vascular
bundles, parallel venation on leaves,
herbaceous stems.
• 2. Dicot stems – vascular bundles are
arranged in a cylinder, branched venation
on leaves, woody stems.
Monocot cross section
Examples of Monocot plants
Dicot cross section
Dicot versus Monocot
Primary Growth of stems
• A. Growth only on the tips of roots
and stems is called primary
growth.
–1. This growth is produced by
cell division in the apical
meristem. This growth takes
place in all seed plants.
Secondary growth of stems
• A. The method of growth in which stems
increase in width is called secondary
growth.
• 1. Conifers and dicots secondary growth
takes place in the lateral meristematic
tissues called the vascular cambium and
cork cambium.
– A. vascular cambium produce vascular tissue
and cork cambium produce outer coverings of
stems.
•Leaves
I.
Leaves 23-4
A. Leaves are the main organ
of a plant that conducts
photosynthesis, making
glucose, by capturing sunlight.
B. Leaves have special cells
(chlorophyll) that allow it to
perform this chemical reaction.
A. Structure and Function
• 1. Mesophyll – leaf ground tissue
–A. Upper Epidermis - covers top
and is sometimes covered with a
cuticle.
–B. Cuticle – waxy covering on the
surfaces of some leaves to protect
and prevent drying out.
• 2. Palisade Cell Layer– Under the
upper epidermis, closely packed cells,
absorb light, lots of chlorophyll.
• 3. Spongy Cell Layer – below the
palisade layer, contains many air spaces
for gas exchange. Also where the vascular
tissue is found.
• 4. Stomata – pore like openings underside
of the leaf (lower epidermis) that allows
carbon dioxide and oxygen to diffuse into
and out of the leaf.
• 5. Guard cells- surround stomata, control
the opening and closing of the stomata by
responding to changes in water pressure.
• 6. Lower Epidermis – Bottom of leaf that
contains stomata’s
• Stomata’s and guard cells