4 - Growth and Development of the Plant

• Plant body consists of a root system and a sheath system
• Root system:

  • Usually underground
  • Anchors plant in the soil
  • Functions in food storage
• Sheath system:

  • Above ground
  • Responsible for photosynthesis, reproduction, and dispersal of food and water conduction
  • Forms the vegetative plant body
• The plant body consists of 3 organs: leaf, stem, and root

  • Leaf: for photosynthesis
  • Stem: provides support
  • Root: for anchorage and absorption of water and minerals
• Patterns of growth and development in plants start with embryogenesis
• Plants have regions of 2 nodes called internodes
• Terminologies:

  • Growth: permanent increase in size, accompanied by differentiation and development
  • Differentiation: process by which cells undergo biochemical and structural changes to perform specialized functions
  • Morphogenesis: development of form or shape of cells and organs, leading to more order or complex state
• Growth in plants occurs in meristems, which are zones where totipotent cells rapidly divide

  • Embryonic tissue regions
  • Formation of new cells
  • Can develop into any type of cell
• Growth patterns in plants include:

  • Periclinial: cell divisions increase thickness of organ, parallel with surface
  • Anticlinal: cell divisions increase in number of layers of cells, producing a plaid-like structure
  • Transverse: anticlinal division at right angles to the long axis, giving rise to complex of parallel longitudinal files of cells
• Features of plant growth:

  1. Primary growth:

  • Length increase due to apical meristems in root and shoot tips

  2. Secondary growth:

  • Increase in girth or diameter due to lateral meristems like vascular cambium and phellogen
• Embryogenesis initiates plant development, transforming a single cell zygote to a multicellular embryonic plant

  • Stages include globular, heart, torpedo, and maturation stages
• Embryogenesis in vascular flowering plants involves double fertilization, producing triploid endosperm and diploid zygote that goes through various stages to form a mature embryo
• Embryo development in "Shepherd’s purse" Capsella bursa-pastoris involves stages like two-celled stage, globular stage, heart stage, and maturation stage
• Axial and radial patterns of tissues are found in plant development, with regions giving rise to the seedling like shoot apical meristem, hypocotyl, epidermis, root, ground meristem, vascular cambium, and quiescent center
• Organogenesis in plants occurs upon germination of seed, where the mature embryo resumes growth and becomes the adult plant, generating organs and tissues of the adult from shoot apical meristem and root apical meristem
• Root development in woody angiosperms involves the pericycle, dermal, vascular, and ground tissue systems, with layers like epidermis, cortex, endodermis, pericycle, primary phloem fibers, secondary phloem, vascular cambium, secondary xylem, and primary xylem
• Stem development in woody angiosperms includes layers like epidermis, cortex, primary phloem, vascular cambium, primary xylem, secondary xylem, second phloem, and pith rays, with differences from root development like the presence of cork cambium, pith composed of parenchyma cells, and the absence of pericycle
• What are the planes of division?

  3 planes

  A) Periclinal division

  B) Radial anticlinal division

  C) Transverse anticlinal division

  
• What growth is this? Primary or secondary?

  Primary

  
• What stage is this?

  Globular stage

  
• What stage is this?

  Heart stage

  
• What stage is this?

  Torpedo stage

  
• What stage is this?

  Maturation stage