Plant tissues

• lenticels


  in the periderm allow for gas exchange between living cells in the stem or root and the outside air
• bark


  consists of all the tissues

  external to the vascular cambium, including secondary phloem and

  periderm
• periderm


  is impermeable to water

  and gasses
• suberin


  Cork cells deposit waxy _____ in their walls, then die
• Cork cambium


  gives rise to cork

  cells that accumulate to the exterior of it - it

  produces compose a layer of periderm that replaces the epidermis
• Dendrochronology


  is the analysis of

  tree ring growth patterns and can be used to study past climate change
• vascular rays


  radial files of

  parenchyma cells that connect secondary xylem and phloem
• Secondary growth

  consists of the tissues

  produced by the vascular cambium and

  cork cambium, simultaneously occur with primary growth
• secondary growth


  occurs in gymnosperms and many eudicots, but is rare in monocots; occurs in stems and roots of woody plants but rarely in leaves
• Veins; protective bundle sheath


  are the leaf's vascular bundles and function as the leaf's skeleton, each of it is enclosed by a
• The vascular tissue of each leaf is

  continuous with the vascular tissue

  of the stem
• spongy mesophyll


  eudicot mesophyll layer whose in the lower

  part of the leaf; the loose arrangement allows for gas exchange
• palisade mesophyll


  eudicot mesophyll layer whose main function is for photosynthesis
• mesophyll


  is sandwiched between

  the upper and lower epidermis
• guard cells


  Each stomatal pore is flanked by two _____, which regulate its opening and closing
• Stomata


  pores for CO2 and O2 exchange is located at the epidermis of the leaves - are also major avenues for evaporative loss of water
• leaf primordia


  Leaves develop from this along the sides of the shoot apical meristem
• Apical Dominance


  The control of the

  shoot tip over the axillary buds
• Axillary buds


  develop from meristematic

  cells left at the bases of leaf primordia • are kept dormant by chemical

  communication from the apical bud
• shoot apical meristem


  is a dome-shaped

  mass of dividing cells at the shoot tip • The leaves of the apical bud protect the meristem
• pericycle


  The vascular cylinder is surrounded by a cell layer called the
• endodermis


  it regulates passage of substances from the soil into the vascular cylinder, innermost layer of the cortex
• Root hairs


  epidermal cells modified

  for absorption, make up 70-90% of the total root surface area
• • Zone of cell division

  • Zone of elongation

  • Zone of differentiation, or maturation


  Growth occurs just behind the root

  tip, in three zones of cells:
• root cap


  protects the root apical

  meristem as it pushes through the soil
• Annuals complete their life cycle in a

  year or less • Biennials require two growing seasons • Perennials live for many years


  Flowering plants can be categorized based on the length of their life cycle
• Plant Growth: Meristematic Tissues

  primary growth and secondary growth occur simultaneously but in different locations
• protoderm > dermal tissue, ground meristem > ground tissue, procambrium > vascular tissue


  During primary growth, cells produced by the meristem give rise to three primary meristems that will produce the mature tissues of the plant
• Cork Cambium


  lateral meristem growth for epidermis or periderm
• Vascular Cambium


  lateral meristem growth for vascular tissues
• lateral meristems


  secondary growth (thickness)
• apical meristems


  located at the tips of roots and shoots - elongate shoots and

  roots, a process called primary growth
• meristems


  Plants can grow continuously due

  to the activity of ______,

  unspecialized tissues composed of

  dividing cells
• indeterminate growth


  Plants grow throughout its life. This is called
• Sclerenchyma; lignin; cellulose


  ground: are rigid because of thick secondary walls strengthened with ____ and ____ that

  resist compression
• sclerenchyma


  ground: dead at functional maturity, structural support
• Collenchyma: pectin


  with polysaccharide ______ (along with

  cellulose) which imparts flexibility to their primary wall
• Collenchyma


  - elongated cells with irregularly thickened

  cell walls that are alive at maturity - it provides structural support to rapidly growing plant parts such as young stems
• Parenchyma: mesophyll


  ground: photosynthetic part of the leaves
• parenchyma


  ground: alive in mature tissue and can divide - soft parts inside the roots, stems, leaves, and flower