PLANT STRUCTURE AND GROWTH

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CHAPTER 35

• PLANT STRUCTURE AND GROWTH

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• ARABIDOPSIS
• MOLECULAR BIOLOGY HAS REVOLUTIONIZED THE STUDY OF
  PLANTS
• IS A MODEL ORGANISM TO STUDY
• TINY GENOME
• SHORT GENERATION SPAN
• HIGH MUTATION RATE

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• ANGIOSPERM 2 CLASSES
• MONOCOTS NAMED FOR A SINGLE COTYLEDON. ORCHIDS,
  BAMBOO, PALM, LILIES, YUCCA, GRASSES, WHEAT, RICE
  AND CORN
• DICOTS 2 COTYLEDONS. ROSES, BEANS, SUNFLOWERS,
  MAPLES AND OAKS

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• ROOT SYSTEMS
• ANCHOR PLANT
• ABSORB WATER AND MINERALS
• CONDUCT WATER AND NUTRIENTS
• STORAGE OF FOOD
• DICOTS TAPROOTS, 1 LARGER VERTICLE ROOT
• MONOCOTS FIBROUS ROOTS. MATS OF THREADLIKE
  ROOTS
• ADVENTITIOUS ROOTS ROOT SYSTEMS ABOVE GROUND

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• SHOOT SYSTEMS
• STEMS ALTERNATING SYSTEM OF NODES AND
  INTERNODES
• AXILLARY BUD THE ANGLE FORMED BY EACH LEAF AND
  STEM
• TERMINAL BUD APEX (TIP) PRESENCE INHIBITS
  GROWTH
• APICAL DOMINANCE AXILLARY GROWTH DUE TO THE
  PRESENCE OF A TERMINAL BUD
• PRUNING STIMULATES GROWTH
• MODIFIED STEMS STOLONS, RHIZOMES, TUBERS AND
  BULBS

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• LEAVES
• SIMPLE
• COMPOUND
• DOUBLE COMPOUND
• BLADE AND PETIOLE ARE MODIFIED LEAVES

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• CONTENTS OF PLANT CELLS
• 1. PARENCHYMAL CELLS LEAST SPECIALIZED, THIN
  PRIMARY FLEXIBLE WALLS, MOST METABOLIC FUNCTIONS
  OCCUR
• 2. COLLENCHYMAL CELLS SUPPORT FOR THE GROWING
  PLANT, SLIGHTLY THICKER PRIMARY WALLS
• 3. SCLERENCHYMA CELLS THICK WALLS, CONTAIN
  LIGNIN, MORE RIGID THAN THE OTHER CELL TYPES.
  LACK PROTOPLASTS AT MATURITY, SPECIALIZED FOR
  SUPPORT (DEAD CELLS)
• -TWO CELL TYPES
• - FIBER LONG AND SLENDER, USED TO
• MAKE ROPE
• - SCLEREIDS SHORTER THAN FIBERS,
• IRREGULAR SHAPE, NUTSHELLS AND
• SEED COATS, GIVES FRUIT ITS TEXTURE

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• 4. XYLEM WATER CONDUCTING CELLS,
• TRACHEIDS DEAD AT MATURITY, SPINDLE SHAPED
  CELLS WITH PITS TO ALLOW WATER TO FLOW FROM CELL
  TO CELL. VESSEL ELEMENTS ARE INDIVIDUAL CELLS
  THAT ARE LINKED TOGETHER TO FORM LONG TUBES OR
  XYLEM VESSELS
• 5.PHLOEM SIEVE TUBES MEMBERS THAT CONDUCT FOOD.
  CHAINS OF CELLS THAT FORM A TUBE,WHICH IS ALIVE
  AT MATURITY.
• COMPANION CELLS CONNECTED TO THE SIEVE TUBE,
  IT CONTAINS ORGANELLES NECESSARY FOR LIFE
  PROCESSES

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• PLANT CELLS (TISSUE SYSTEMS)
• DERMAL TISSUE OR EPIDERMIS. SINGLE LAYER THAT
  COVERS AND PROTECTS NEW GROWTH OF THE PLANT.
  ROOT HAIRS EMERGE. SECRETES THE CUTICLE
• VASCULAR TISSUE XYLEM AND PHLOEM, TRANSPORT AND
  SUPPORT
• GROUND TISSUE SYSTEM PRIMARILY PARENCHYMA AND
  SOME COLLENCHYMA WITH LITTLE SCLEREMCHYMA CELLS.
  FILLS THE SPACE BETWEEN DERMAL AND VASCULAR
  SYSTEM. PHOTOSYNTHESIS, STORAGE AND SUPPORT

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• PLANT GROWTH
• INDETERMINATE MOST PLANTS GROW AS LONG AS THEY
  LIVE
• DETERMINANT CERTAIN PLANT ORGANS STOP GROWING
  (LEAVES AND FLOWERS)
• ANNUALS 1 LIFE CYCLE PER YEAR (WEEDS, FLOWERS)
• BIENNIAL 2 SEASONS PER LIFE CYCLE (CARROTS OR
  BEETS)
• PERENNIALS LIVE MANY YEARS (TREES, SHRUBS)

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• PLANT GROWTH
• MERISTEMS EMBRYONIC TISSUE, GROWTH TISSUE
• APICAL MERISTEMATIC TISSUE
• PRIMARY GROWTH, ELONGATION
• FOUND IN THE TIPS OF THE ROOTS AND SHOOTS
• HERBACEOUS (NONWOODY) PLANTS ONLY DEMONSTRATE
  PRIMARY GROWTH

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• LATERAL MERISTEMATIC TISSUE
• SECONDARY GROWTH
• WOODY PLANTS
• THICKER, TOUGHER
• ADDS LAYERS TO VASCULAR TISSUE
• WOOD IS SECONDARY XYLEM

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• PRIMARY GROWTH, PRIMARY PLANT BODY
• ROOT CAP PROTECT THE ROOT TIP. SECRETES A
  POLYSACCHARIDE SLIME THAT WILL LUBRICATE THE
  SOIL AROUND IT
• ZONE OF DIVISION INCLUDES APICAL MERISTEM AND
  ITS DERIVATIVES, CALLED PRIMARY MERISTEM
• QUIESCENT CENTER POPULATION OF CELLS THAT
  FUNCTION AS CELL RESERVES FOR NEW GROWTH

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• PROTODERM PRODUCE ROOT, EPIDERMIS
• PROCAMBIUM PRODUCE DERMIS AND VASCULAR BUNDLES
• GROUND MERISTEM PRODUCE GROUND TISSUE
• THE ZONE OF CELL DIVISION BLENDS INTO THE ZONE OF
  ELONGATION AND THE CELLS ELONGATE INTO THE ZONE
  OF MATURATION
• ALL THREE TISSUES COMPLETE DIFFERENTIATION

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• CORTEX THE REGION OF THE ROOT BETWEEN THE STELE
  AND EPIDERMIS WHICH IS FILLED WITH PARENCYMA
  CELLS AND CONTAINS STORED FOOD AND MINERALS
• ENDODERMIS INNERMOST LAYER OF THE CORTEX, ONE
  CELL LAYER THICK. FORMS THE BOUNDARY BETWEEN
  THE CORTEX AND THE STELE
• LATERAL ROOTS ARISE FROM THE PERICYCLE WHICH IS
  THE OUTERMOST LAYER OF THE STELE

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• LEAF ORGANIZATION
• UPPER EPIDERMIS
• CUTICLE
• MESOPHYLL LAYER
• PARENCHYMA CELLS WITH CHLOROPLASTS
• PALISADE PARENCYHMA OR SPONGY PARENCHYMA
• LOWER EPIDERMIS
• STOMATES, GUARD CELLS (GAS EXCHANGE AND
  TRANSPIRATION)

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• SHOOT CONSTRUCTION
• SERIAL DEVELOPMENT OF NODES AND INTERNODES
• AXILLARY BUD
• SERIAL ADDITION OF DIFFERENT SEGMENTS AT
  DIFFERENT TIMES
• AS OPPOSED TO HUMANS WHERE OUR APPENDAGES ARE THE
  SAME SIZE THROUGHOUT ADULT LIFE

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• LATERAL MERISTEMS
• SECONDARY GROWTH WHICH INCREASES GIRTH
• RARELY OCCURS IN MONOCOTS
• 2 TISSUE TYPES
• VASCULAR CAMBIUM PRODUCE SECONDARY XYLEM (WOOD)
  AND PHLOEM
• CORK CAMBIUM PRODUCE A THICK TOUGH COVERING FOR
  STEMS AND ROOTS THAT REPLACE EPIDERMIS

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• VASCULAR CAMBIUM
• APPEARS AS A RING
• IS A CYLANDER OF MERISTEMATIC CELLS THAT FORM
  FROM SECONDARY TISSUE
• ACCUMULATION ACCOUNTS FOR THE INCREASE IN
  DIAMETER OF A WOODY PLANT
• PRODUCES SECONDARY XYLEM TO ITS INTERIOR AND
  SECONDARY PHLOEM TO ITS EXTERIOR
• GROWTH OCCURS SIMULATANEOUSLY

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• RAY INITIALS CAMBIUM CELLS THAT PRODUCE RADIAL
  FILES OF PARENCHYMA CELLS KNOWN AS XYLEM RAYS
  AND PHLOEM RAYS WHICH TRANSPORT WATER AND
  NUTRIENTS
• FUSIFORM INITIALS CAMBIUM CELLS FOUND WITHIN
  VASCULAR BUNDLES. PRODUCE NEW VASCULAR TISSUE
  THAT WILL FORM SECONDARY XYLEM AND PHLOEM

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• WOOD CONSISTS MAINLY OF TRACHEIDS, DEAD
  LIGNIFIED CELLS THAT GIVE WOOD ITS HARDNESS AND
  STRENGTH
• BARK MORE INCLUSIVE THAN PERIDERM. IT REFERS TO
  ALL THE TISSUE EXTERNAL TO THE VASCULAR CAMBIUM
• CORK CAMBIUM
• PERIDERM LAYERS OF CORK PLUS CORK CAMBIUM. A
  PROTECTIVE COAT WHICH REPLACES THE EPIDERMIS OF
  THE PRIMARY BODY

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• LENTICILS SPONGY AREAS FOUND IN THE BARK FOR
  GAS EXCHANGE
• ROOTS ONLY THE YOUNGEST ROOTS ABSORB WATER AND
  NUTRIENTS