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chapter 7: Roots, No axillary buds are found in individual roots or in the…

- - - - much larger
      - branch roots
      - radicle
        
        embryonic root
        
        present in seed
        
        grows extensively
        after germination
      - largest root in system
  - - - highly ramified
      - prominently swollen
      - secondary growth
        
        woody
        
        perennial
        
        produce bark and wood
      - produce more lateral roots
    - - soil:
        
        dry
        
        hard
        
        poor
  - - - grows out
      - first stage of fibrous system
      - plant ages
        
        more primordia initiated
        
        stem tissue
      - adventitious roots
        
        not radicle
        
        not from pre-existing
        
        increase absorption
        
        increase transport capacities
        
        rhizomatous eudicots
        
        stoloniferous eudicots
  - - - root tip
      - discrete apical meristem
        
        protected
        
        root cap
        
        thick layer of cells
        
        forced through soil
        
        constantly worn down
        
        renewed by cell
        multiplication
        
        mucilage
        
        dictyosomes
        
        complex polysaccharide
        
        lubricates root passage through soil
        
        causes release of
        nutrient ions
        
        permits diffusion of ions
        
        rich in carbohydrates and amino acids
      - longitudinal growth
    - - extreme tip
      - pushes through soil
    - - just behind root cap and
        root apical meristem
      - few millimeter long
      - cells undergo expansion
      - division
      - root hairs
        
        behind elongation zone
        
        epidermal cells extend
        
        narrow trichomes
        
        only in part of root
        
        increase surface area
        
        enter any crevice
        
        extract water
        
        extract minerals
      - carbon acid
        
        root hair respiration
        
        soil water
        
        helps release ions
        
        from soil matrix
- - - - firm acnhoring
      - provides stability
    - - cylindrical shape
      - all side absorb
        
        distributed
      - growth through semisolid resistant medium
    - - cytokinin
      - gibberellin
      - shoot growth
      - development
    - - selectively advantageous
    - - taproots
        
        fleshy
        
        carbohydrate storage
        
        carrots, beets and radishes
- - - - specific structure
      - specific growth patterns
    - - cells closest to root meristem
      - cell division
      - transverse walls
      - files of cells
      - pushed forward.
        
        develop starch grains
        
        ER displaces to
        forward end
        
        detect gravity
      - simultaneously
        
        cells on edges
        
        grow towards sides
        
        structure changes
        
        metabolism changes
        
        ER less conspicuous
        
        starch grains digested
        
        dictyosomes descrete copious
        amount of mucilage
        
        middle lamella breakdown
        
        releases cells
        
        crushed in expansion of root
        
        proliferate
  - - - orginate in meristem
      - extend mature root tissues
    - - more orderly than shoot
      - no leaf primordia
      - no leaf traces
      - no axillary buds
    - - tritiated thymidine
      - central cells not synthesizing DNA
      - nuclie dont take up
      - don't become radioactive
      - quiescent center
        
        inactive central region
        
        cells more resistant
        
        harmful agents
        
        radiation
        
        toxic chemicals
        
        primarily reserve for healthy cells
  - - - visible pattern
      - outermost cells
        
        protoderm
        
        differentiate into epidermis
      - center
        
        provascular tissue
        
        primary xylem
        
        primary phloem
    - - provascular
      - protoderm
    - - protoxylem
      - protophloem
    - - metaxylem
      - metaphloem
      - larger cells
    - - minerals penetrate deep
        
        apoplast
        
        diffusing along
        
        thin
        
        fully hydrated
        
        young walls
        
        intercellular space
  - - - root hairs grow out
        
        increased absorption water
        
        increased absorption of minerals
        
        thin cuticle on epidermal cells
        
        cortex cells enlarge
        
        tranfer of minerls
        
        from epidermis to vascular tissue
        
        apoplastic transport
        
        diffusion through walls
        
        diffusion through intercellular space
        
        symplastic transport
        
        absorption into cytoplasm
        
        transfer cell to cell
        
        through plasmodesmata
      - zone of maturing
        
        minerals don't have
        free access to
        vascular tissue
        
        innermost layer cortical cells
        
        differentiate
        
        cylinder
        
        endodermis
        
        tangential walls
        
        closest to vascular tissue
        
        cortex
        
        no control
        
        mineral movement
        
        within intercellular space
        
        thin primary walls
        
        radial walls
        
        4 more items...
        
        casperian strips
        
        control types of minerals
        
        xylem water stream
        
        impermeable
      - pericycle
        
        between vascular and ER
        
        irregular region
        
        parenchyma cells
        
        lateral roots initiated
    - - only grow days
      - die/ degenerate
      - absorption water minerals slow
        
        does not stop
      - root pressure
        
        powerful absorption water
        
        absorption minerals
        
        water pressure
    - - only casparian strips
      - slow to develop
    - - watertight sheath
      - keep water in
      - cells uncharged
      - becomes root surface
        
        until bark forms
- - - - stored in root
      - produce new shoot
    - - less change
      - tmeperature
      - humidity
  - - - transport nutrients to stem
      - transport water to stem
    - - secondary growth
        
        woody
        
        strong supports
        
        permits branch extension
    - - upperside grows
      - brace trunk
      - prevent being blown over
  - - - live on branches
        
        spread across
        
        dangle freely
    - - root epidermis
      - several layers
        
        large
        
        dead cells
        
        white in appearance
      - waterproof barrier
        
        no water leaves
  - - - uppermost contracts slowly
      - stem pulled down
      - base of shoot soil level
      - changes shape of cortex cells
        
        shorten
        
        expand
        
        vascular tissue buckles
        
        undulate
        
        stop conducting
  - - - ectomycorrhizal relationship
        
        fungal hyphae
        
        penetrate
        
        outermost root cortex
        
        never invade cells
      - endomycorrhizal association
        
        can not pass casparian strips
        
        invade cell
        
        do not break host plasma
        
        don't break vacuole membrane
        
        branch repeatedly inside cell
        
        small structure
        
        abuscule
  - - - main growth limiting factor
    - - chemical conversion
    - - bacterium
      - pushes into cell
      - tube-like invagination
    - - infection thread spreads
      - penetrating cells
      - roots inner cortex
      - adjacent cells cortical cells mitosis
      - released from infection thread
        
        enters cytoplasm