Plant History

  • Canada has at least 5000 different plant species.  These range from flowering plants, to large trees, to agricultural plants
  • The earliest plant is believed to have evolved 430 million years ago
  • The first land plants were mosses and ferns
  • All land plant life can be traced back to those species.
  • Classification of Plants:
  • Plants can be divided into 2 categories: Non-Vascular and Vascular
  • Non-vascular plants do not have any internal specialized tissues
  • They require moist or aquatic environments to live and reproduce
  • Example: Mosses
  • Vascular plants have specialized tissues within their structure that transport nutrients.
  • The two main tissues are xylem which transports water and phloem which transports nutrients

Plant Classification

  • Vascular plants are the category that most plants belong to.  For that reason we need to further sub-divide them.
  • Vascular plants are divided into two categories: gymnosperms and angiosperms
  • Gymnosperms have seeds that are found in a protective cone
  • Example Pine Tree
  • Angiosperms are flowering plants and have seeds that are found in fruit
  • Example Tomato Plant
  • Angiosperms have more species than Gymnosperms so this category is divided into two as well
  • Angiosperms are divided into two category based on their seed structure
  • They are divided into monocots or dicots
  • Monocot seeds have seed section and dicots have two seed sections.

Plant Growth

  • Plants have the ability to use the sun’s energy to make their own food in the process of photosynthesis
  • Carbon dioxide + Water > Sugar + Oxygen
    • They also need to use the sugar and oxygen they create to get energy for their growth
    • Sugar + Oxygen > Water + Carbon Dioxide + Energy
      • In order to grow and thrive all plants must have
      • Carbon Dioxide
      • Sunlight
      • Water
      • Oxygen
      • Carbohydrates (Sugar)
      • Nitrogen in the form of Nitrates
      • Room to expand (up, down and out)

In addition to these 7 basic needs, there are many other factors that determine how well a plant will grow and what types of plants grow.  They are:

  • Day Length
  • Amount and strength of light
  • Temperature
  • Heat
  • Cold
  • Water availability
  • pH
  • Factors Details
  • Daylength
    • Plants utilize daylength as a cue to promote their growth in spring and prepare them for the cold weather.  Many plants require specific daylength conditions to initiate flowers.

Amount and Strength of Light

  • Light is the energy source for plants.  Cloudy, rainy days or the shade cast by nearby plants and structures can significantly reduce the amount of light available.  Shade adapted plants cannot tolerate the bright light of full sun.  Plants survive only where the amount is within a range they can tolerate.

Temperature

  • Plants grow best within an optimum range of temperatures; and the range may be wide for some species, narrow for others. Plants survive only where temperatures allow them to carry on life-sustaining chemical reactions.

Cold

  • Plants differ in their ability to survive cold temperatures.  Some tropical plants are injured by temperatures below 16°C.  Arctic species can tolerate temperatures well below zero.   The ability of a plant to withstand cold is a function of the degree of dormancy present in the plant, its water status, and general health.  Exposure to wind and bright sunlight or rapidly changing temperatures can also compromise a plant’s cold tolerance.

Heat

  • Heat tolerance varies widely from species to species.  Many plants that naturally grow in arid tropical regions are naturally very heat tolerant, while subarctic plants and alpine plants show very little tolerance for heat.  High night temperatures are often the most limiting factor for many plants.

Water Availability

  • Different plants have different water needs.  Some tolerate drought during the summer but need winter rains.  Others need a consistent supply of moisture to grow well.

pH

  • The ability of plant roots to take up certain nutrients depends on the pH of your soil.   Most plants grow best in soils that have a pH near 7.0.  Lime (Calcium Carbonate) can be used to raise pH and materials containing sulfates such as aluminum sulfate and iron sulfate can be used to lower pH.  The solubility of many trace elements is controlled by pH, and only the soluble forms of these important micronutrients can be used by plants.

Soil Types

  • Another regulator of plant growth is soil type.
  • Soil is divided into 3 main categories: Sand, Silt and Clay
  • All soil is a combination of these 3 types
  • Sand silt and clay are different based on particle size.  Sand has the largest particle size, then silt and then clay
  • In addition to particle size the amount of organic material in the soil (called humus) also influences soil properties
  • Peat is decayed vegetative matter and can be added to soil to give it higher humus

Soil Types Characteristics

  • These are the main types of soil
  • Sandy soil
  • Silty soil
  • Clay soil
  • Loamy Soil
  • Peaty Soil
  • Chalky Soil

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