Theory:

Plants mostly can be classified into three categories based on the nature of the stem and growth habits:
  1. Herbs
  2. Shrubs, and
  3. Trees
What are Herbs?
Small plants with soft, tender (stems that easily bend), slender, and green stems are known as Herbs.
  • Herbs are short plants which do not have woody stems.
  • They do not have many branches.
  • They have a short life span and lives for mostly one to two seasons.
Example:
Tomatoes, radish, ginger, turnip, parsley, sunflower, ginger are examples of herbs.
tomatoes-5414735_1920.jpg
Tomatoes  
 
parsley-261039_1920.jpg
Parsley
What are Shrubs?
Medium-sized plants which have branches near the base of the stem are known as Shrubs.
  • The stem of a shrub is hard rather than being thick.
  • They are bigger or taller than the herbs.
  • Have a life span more than that of the herbs.
Example:
Tulasi, lemon, croton, jasmine, bougainvillaea are examples of shrubs plants.
tulsi-plant-500x500.jpg
Tulsi plant
 
Garden_croton_(Codiaeum_variegatum)_variety_1 (1).jpg
Croton
What are Trees?
Plants that are tall, big, and which have a thick, hard stems are known as Trees.
  • They have a trunk (main stem) that has branches and leaves that arise from it.
  • They have a large life span.
Example:
Mango, banyan, neem, oak, palm, and coconut are examples of trees.
brazilwood-893551_1920.jpg
Coconut tree
 
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Banyan tree
Reference:
https://pixabay.com/photos/tomatoes-fruits-bush-tomatoes-5414735/
https://pixabay.com/photos/parsley-seasoning-greens-salad-261039/
https://www.indiamart.com/avmnursery/tulsi-plant.html
https://commons.wikimedia.org/wiki/File:Garden_croton_(Codiaeum_variegatum)_variety_1.jpg
https://pixabay.com/photos/brazilwood-beach-coconut-trees-893551/
https://pixabay.com/photos/nature-banyan-tree-tree-landscape-2932531/