Transcript Vascular Tissue

Patterns of Structure and Func
in Plants
Brain Viagra
In The News
Vascular Plants
• Have transport system
– Water
– Nutrients
• Allows for larger size
Organization of Vascular Plant
• Below ground root system
– Roots for absorption
• Above ground shoot system
– Stems & leaves
• Both have growth zones
Tissue Types of Vascular Plants
(Differentiated Tissue)
• Vascular tissue
– Circulatory system
• Ground tissue
– Embeds vascular tissue
– Most of plant tissue
– Stores carbohydrates
• Dermal tissue
– Protective covering
Meristem Tissue
(Undifferentiated Tissue)
• Area of cell division
• Gives rise to other tissue types
• Results in plant growth
Vascular Tissue
• Xylem
– Transports
• Water
• Nutrients
– Conducting cells
• Tracheids
• Vessel elements
– Cells die before becoming functional
Vascular Tissue
• Phloem
– Conducts
• Carbohydrates
• Minerals
– Cells
• Sieve-tube members
– Living cells
– Cytoplasm, no nuclei
• Companion cells
– Nuclei
– Secrete into & remove from sieve-tube
members
Ground Tissue
• Three cell types
– Parenchyma cells
– Collenchyma cells
– Sclerenchyma cells
Parenchyma
• Photosynthesis and storage
• Thin walled
• Most common cell type
Collenchyma
• Support tissue
• Unevenly thickened cells
• Bundles of supportive columns
Sclerenchyma
• Help in support and strength
• Dead, hollow cells with thick walls
• Fibers and sclerids
Dermal Tissue
• Covers plant
• Cells
– Mostly epidermal (cuticle)
– Guard cells
• Surround stomata
– Trichomes
• Outgrowths of epidermis
• Bark replaces dermal tissue in woody plants
Meristematic Tissue
• Meristems
– Areas of undifferentiated cells
– Undergoes mitosis
• Primary growth
– At tips of roots & shoots
• Secondary growth
– Cylinder of meristematic tissue
– Found in woody plants
Organs of Vascular Plants
• Roots
• Stems
• Leaves
Roots
• Absorb water & minerals
• Anchor the plant
• Storage (Some Roots)
Root Tissue Structure
Root Growth
• Meristem tissue at tip of root
Root Hairs
• Increase surface area for absorption
Types of Roots
Taproot
Prop Root
Fibrous Root
Essential Nutrients Delivered by
Roots
Need for Nutrients
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Plants produce carbohydrates from nonmineral nutrients (photosysthesis)
Need nucleic acids, proteins, fats, & vitamins
These are produced from carbohydrates and mineral nutrients
Nutrient deficiency impairs growth
Stems
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Support leaves
Transport fluids
Have many shapes
Storage
Stem Structures
• Nodes
– Areas where leaves form on stem
• Internodes
– Areas between nodes
• Lateral buds
– Side shoots from stem
Stem Transport System
Vascular Cambium
• Growth tissue in woody stems
• New xylem & phloem is formed
Secondary Growth in Woody Stems
Wood of Trees
• Accumulated secondary xylem
• Hardwood – wood of dicot trees
• Softwood – wood of conifers
• Not accurate descriptions of wood density
Tissues in Tree Cross Section
Leaves
• Sites of photosynthesis
• Blade = flattened portion
• Petiole = stalk
Dicot vs. Monocot Leaves
• Monocot – veins parallel
• Dicot – net-like
Internal Leaf Structure
Openings in Leaf Tissue
• Used for respiration
• Stomata – openings
• Guard cells – regulate opening
Transpiration
• Water exiting leaf openings
• Fluids move by transpirational pull or (adhesioncohesion-tension theory)
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Water evaporates from airspaces within leaves
Water in mesophyle moves into empty spaces
Results in pull of water in xylem
Molecules pulled up (adhesion & cohesion)
Water (by osmosis) and minerals (by active transport)
enter through root
Bulk Flow or (pressure flow)
• Fluid (sap) is also transported by phloem
• Transports products of photosynthesis
• Bulk flow = pressure flow
– Companion cells actively transport sucrose into sieve
tube member cells, water follows by osmosis
– High pressure develops in phloem near the source
– Low pressure in sink (where sucrose is used)
– causing the rapid flow of sap
Nonvascular Plants
• No true roots, stems or leaves
• some have stems and leaf-like
structures
• Outer layer of epidermis
• Parenchyma cells inside
• Some have central strand of waterconducting cells
• No other vascular tissues
Rhizoids
• Anchor some nonvascular plants
• No role in absorption
End chapter 24