Download Plant Structure, Growth and Development

Plant Structure, Growth and
Development
Chapter 35
Basic Morphology
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Morphology = external body form
Anatomy = internal structures
Monocot/dicot comparison
How do roots and shoots reflect the
evolutionary history of plants as terrestrial
organisms?
• Plants live in 2 very different environments at
the same time; air and soil
• Roots dig underground for water and minerals
• Shoots are above ground with adaptations for
gas and light retrieval
Roots
• Anchors plant
• Structures for absorption of water and
minerals
• Food storage
• Examples:
• Fibrous root
• Tap root
• Root hairs
Modified Roots
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Prop roots
Storage roots
Aerial roots
Air roots
Stem Morphology
• Nodes – points where leaves attach
• Internodes – stem segment between nodes
• Axillary bud – usually dormant embryonic
bud
• Terminal bud – bud on shoot tip usually has
developmental leaves
• What is apical dominance?
• Why do plant owners pinch back
houseplants?
Modified stems
• Stolons
• Rhizomes
• Bulbs
Leaves
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Flattened blades
Petioles – joins leaf to stem node
Monocot leaves have parallel veins
Dicot leaves have multi-branched veins
Modified Leaves
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Tendrils
Spines
Storage leaves
Reproductive leaves
Bracts
Anatomy
• Parenchyma cells
– Most abundant cell type
– Unspecialized
– Thin primary cell walls
– Photosynthesis and storage
– Some store starch
• Collenchyma cells
– Thick primary cell wall
– Lack secondary cell walls
– Functions in support for young plant (no lignin)
• Sclerenchyma Cells
– Support
– Thick secondary cell walls strengthened by lignin
• Fibers
• Sclerids
• Tracheids and Vessel elements
– Xylem cells
– Functionally dead at maturity
– Tracheids are long and thin
– Vessel elements are wider and shorter and better
at conducting water (in angiosperms)
• Sieve Tube Members (alive)
– Transports sucrose and other compounds
– Chain of cells called phloem
• Companion cells
– make proteins for sieve tube member
– Help load sugar into the sieve tube members
Tissue systems
• Dermal tissue:
• Epidermis
– Protection
– Waxy cuticle
– Root hairs
– Houses guard cells in the leaf
• Vascular tissue
– Xylem and phloem
– Transport functions
• Ground tissue system
– Mostly parenchyma that fills space between
dermal and vascular tissue system
– Diverse functions:
• Photosynthesis
• Storage
• support
Meristems
• Why do most plants grow throughout their
lives?
– Indeterminate growth-always have embryonic,
developing and maturing organs
• Animals move through their environments,
plants grow
• Meristem locations determine growth
Which growth
involves the lateral
meristems?
Primary Growth of Roots
Root Cross Sections
Stem cross sections:
Leaves
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What is the ground tissue of the leaf?
Mesophyll
How is the mesophyll arranged?
Spongy and pallisade regions
Secondary growth
• Growth in girth
• Two lateral meristems:
– Vascular cambium
– Cork cambium
• Secondary xylem accumulates while
secondary phloem is sloughed off
Shoot Growth