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• Plants stay in one place, extend their roots and shoots to harvest diffuse resources, and make their own food through photosynthesis
• The structure of a plant's body is dynamic, because most plants exhibit indeterminate growth, in which they grow throughout their lives

  
• Resources plants need for photosynthesis


  • Light
  • Carbon dioxide
  • Water

  
• Nutrients plants need to synthesize macromolecules


  • Nitrogen
  • Phosphorus
  • Potassium
  • Magnesium
• Root system


  Anchors the plant and takes in water and nutrients from the soil
• Shoot system


  Harvests light and carbon dioxide from the atmosphere to produce sugars
• Root and shoot systems are connected by vascular tissue, which facilitates transport between them
• Importance of surface area/volume relationships


  • Absorption takes place across a surface, but the cells that use the absorbed light and molecules occupy a volume
  • A plant body is more efficient as an absorbance-and-synthesis machine when it has a large surface area relative to its volume

  
• Root system


  • Has a vertical section called a taproot and numerous lateral roots that run more or less horizontally
  • Anchors the plant in the soil, absorbs water and ions from the soil, conducts water and selected ions to the shoot, and stores material produced in the shoot for later use

  
• Levels of diversity in root systems


  • Morphological
  • Phenotypic plasticity
  • Modified roots
• Morphological diversity


  Apparent in prairies or grasslands, where natural selection has favoured structures that minimize competition for water and nutrients
• Phenotypic plasticity


  Roots can change their form in response to environmental conditions, even in genetically identical individuals
• Examples of modified roots


  • Prop roots
  • Aerial roots
  • Pneumatophores
  • Contractile roots
  • Parasitic roots
  • Food storage roots
  • Water storage roots
  • Buttress roots

  
• Shoot system


  Consists of one or more stems, which are vertical aboveground structures with nodes, internodes, leaves, and buds

  
• Levels of diversity in shoot systems


  • Morphological diversity
  • Phenotypic plasticity
  • Modified shoots
• Plants cannot live on sugar alone. They also need to synthesize all of their own macromolecules
• Morphological diversity in shoot systems


  Allows plants of different species to harvest light at different locations, minimizing competition and thriving in a wide array of habitats
• Plants need elements in addition to those available from carbon dioxide and water
• Phenotypic plasticity in shoot systems

  The size and shape of an individual's shoot system can vary dramatically based on variation in growing conditions
• Soil provides most of these nutrients
• Essential nutrient


  An element that is required for both normal growth and reproduction and for a specific structure or metabolic function

  
• Examples of modified shoots


  • Stems of cacti that store water
  • Stolons that run over the soil surface
  • Rhizomes that grow underground horizontally
  • Tubers that are rhizomes modified to store carbohydrates
  • Thorns that protect the plant from herbivores

  
• For most vascular plants, 17 elements are essential
• Carbon, hydrogen, and oxygen typically make up about 96 percent of the dry weight of a plant
• The major distinguishing feature between monocot and eudicot stems is the organization of the vascular tissue system

  
• Essential nutrients


  • Obtained from water or carbon dioxide
  • Soil elements (macronutrients and micronutrients)

  
• Leaf


  In most plant species, the vast majority of photosynthesis occurs in leaves, which have a relatively large surface area available for absorbing photons

  
• Macronutrients


  The building blocks of nucleic acids, proteins, carbohydrates, phospholipids, and other key molecules required in relatively large quantities
• Limiting nutrients


  Macronutrients that commonly act as limits on plant growth (N, P, and K)

  
• Levels of diversity in leaves


  • Morphological diversity
  • Phenotypic plasticity
  • Modified leaves

  
• Morphological diversity in leaves


  Leaves can vary in size, shape, and arrangement on the stem

  
• Micronutrients


  Required in very small quantities, usually function as cofactors for specific enzymes (e.g. iron, zinc, boron, copper, nickel)

  
• Phenotypic plasticity in leaves


  Leaves can vary in size and shape in response to environmental conditions, such as sun exposure
• Weathering


  Rain, running water, and wind break down solid rock into soil
• Gravel, sand, silt, or clay


  Rock fragments that are the first ingredients in soil
• Examples of modified leaves


  • Cactus spines
  • Onion bulbs
  • Leaves of succulents that store water
  • Tendrils of vines
  • Bright red leaves of poinsettias
  • Leaves that function in carnivory

  
• Humus


  Organic matter from dead cells and tissues of organisms in the soil
• Primary growth


  Plants grow continuously because they have meristems - populations of undifferentiated cells that can continuously divide and produce new cells
• Mature soils are a complex mixture of organic and inorganic components
• Soil-dwelling organisms include a variety of fungi and animals, along with vast numbers of bacteria, archaea, and microscopic protists