PLANT STRUCTURE AND FUNCTION

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PLANT STRUCTURE AND FUNCTION

• D Jones

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Plant Cell Types

• parenchyma
• metabolism
• storage
• contain plastids that
  store store starch
  
• support with growth
• sclerenchyma
• support without growth
• two forms
• fibers (flax and hemp)
• sclereids (nutshells)

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• Xylem
• water conducting
• dead at maturity
• tracheids
• long, thin, tapered ends
• vessel elements
• wider, shorter, thin walled, less tapered
• Phloem
• food conducting
• live at maturity
• sieve-tube members
• Have sieve plates
• companion cells

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Tissue Systems

• dermal
• epidermis
• tightly packed cells
• cover and protect
• vascular
• xylem phloem
• transport support
• ground
• mostly parenchyma
• photosynthesis, storage support
• collenchyma
• sclerenchyma

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Plant Systems

• roots
• Stems
• leaves
• flowers seeds

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Functions of Roots

• absorb water and nutrients
• anchor plants
• conduct water and nutrients
• store food

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Types of Roots

• fibrous roots
• mat of thread-like roots
• just below soil surface
• found in monocots
• tap roots
• one long root
• deep into soil
• found in dicots

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Root Cross Section
Monocot
epidermis
cortex
endodermis
xylem
pericycle

• Dicot

xylem
phloem
cortex
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Tissue Characteristics Functions
Tissue Characteristics Function
Cortex Cellular spaces for aeration Stores starch
endodermis Tightly packed produce suberin(creates water barrier called casparian strip Control movement of water into center of root and prevent outward movement
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Root hairs

• give surface area for absorption

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Functions of Stems

• transport materials
• support
• storage

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Types of Stems

• Herbaceous
• in annuals
• green (photosynthesize)
• pliable
• Woody
• in perennials
• have bark
• inflexible

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Stem Cross Sections
monocot
vessel element (xylem)
air space
phloem
dicot
phloem
xylem
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Tissue functions

• epidermis produces waxy cuticle of cutin to
  protect from water loss
• cortex ground tissue containing chloroplasts
• vascular cylinder xylem, phloem and pith

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Woody Stem
periderm
cork cambium
cortex
phloem
pith
xylem
vascular cambium
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Tissue functions

• vascular cambium produces new xylem and phloem
• periderm (bark or cork) protects from water loss
• cork cambium produces periderm
• Sapwood outermost water-conducting xylem
• Heartwood innermost supporting xylem

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Leaf Functions

• photosynthesis food production

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Functions of Leaves

• photosynthesis

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Types of Leaves

• Simple
• compound
• Pinnate
• palmate

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Leaf Cross Section
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Tissue Functions

• epidermis covered by waxy cuticle of cutin that
  limits water loss
• palisade mesophyll specialized for
  photosynthesis tightly packed
• spongy mesophyll air spaces allow gas exchange
• guard cells open and close stomata to allow
  gas exchange and limit water loss
• vascular bundles transport of water and food

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Stomata Functioning

• guard cells have thicker cell walls near the
  stomata
• when water moves into guard cells they expand and
  open
• when water moves out the guard cells close

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Factors that Affect Stomata

• temperature stomata close limiting water loss
  when the temperature is high
• CO2 concentration stomata open when CO2 is low
  allowing photosynthesis
• day/night stomata open during the day and close
  at night

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Flowers and Seeds

• reproduction

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Flower structure
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Functions of Flower Parts

• petals attract birds and insects
• sepals protect flower buds
• stamen male structures that produce pollen
• pistil female structures tha produce ovules

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Seeds
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Tissue Functions

• seed coat - protection
• Endosperm - storage
• Cotyledon - storage
• epicotyl becomes shoot tip
• hypocotyl becomes shoot
• radical becomes root

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Monocot /Dicot Comparison