5 Major types of classification of plants

Introduction

Plant classification depending on the structure of tissues

1. Vascular Plants/Tracheophytes
   These plants contain vascular tissues in them. Their function is that they aid in water and mineral transportation from soil to various parts of plants. Vascular tissues present in plants are xylem and phloem. Presence of vascular tissues helps plants to grow large in size as enough water and nutrients get absorbed from the soil to the roots and from there they reach every part of the plant.
   Xylem-
   Composition: Made up of non-living cells such as vessel elements and tracheids
   Function: Helps in transporting dissolved minerals and water.
   Phloem-
   Composition: Made up of living cells such as sieve tubes, fibres, parenchyma cells, companion cells
   Function: Helps in transporting food.
2. Non-Vascular Plants
   As the name itself suggests, they do not contain vascular tissues in them. These plants are less advanced when compared to vascular plants and are small in size because of the absence of vascular tissues such as xylem and phloem which help in transportation of water and nutrients from the soil to various parts of the plants. Not only vascular tissues, but they also lack wood, leaves, roots and stems. Reproduction takes place through spores. Though they do not contain roots but contain little hair-like structures known as rhizoids that aid to anchor. Thus, they do not grow everywhere and are only limited to some habitats. These plants are considered to be the earliest living ones.
   Example: Phylum Bryophyta.
   Function of non-vascular plants: They decrease erosion of soil near water bodies.

• Angiosperms
  Angiosperms are complex vascular plants. They are seeded and flowering plants. After the fertilization process, the ovule present into an enclosed ovary develops into a seed. They may be monocot or dicots. Flower may carry male or female or both reproductive systems. There are around 3,00,000 species of angiosperms present on the planet. They are adapted to both freshwater and saltwater environment. They include herbs, shrubs, trees, bulbs and epiphytes. They are so diversely found in every habitat because they can adapt to different regions and temperatures. Because of this adaptability, their root system is extensively developed which, in turn, help in absorption of water and minerals from the soil and transport it to the various parts of the plants.
• Pteridophytes/ Sporophylls
  These vascular plants, unlike angiosperms, do not contain seeds. For reproduction, they do not use cones, seeds or flowers. Their leaves contain spores on their underside. By using spores, they reproduce. There are around 12,000 species of pteridophytes. Majority of them are found in tropical habitats. They too have adapted to various habitats and are found in aquatic bodies and cold regions. Their leaves are known as fronds which at maturity unroll. Their stems are known as rhizomes.
  Example: Ferns
• Gymnosperms
  They are seeded vascular plants. Their seeds are in the form of cones which can be both male and female ones. They are considered to be the oldest plants on the earth. They are found in arctic and temperate regions.
  Examples: Pines, firs, spruce

Plant classification based on seed structure

1. Seed plants/ Spermatophytes/ Phanerogams
   These plants contain seeds and reproduction takes place through them.
   Examples: Maples, Pines
2. Seedless plants
   These plants do not contain seeds. On the underside of fronds which are nothing but their leaves, they contain spores. Reproduction takes place through them.
   Examples: Club Mosses, ferns, horsetails

• Angiosperms
  These are flowering plants containing seeds in a shell-like enclosed structure which is known as a fruit. There are around 2,50,000 species of angiosperms present.
  Angiosperms are further divided into-
  
  1. Monocots-
     Seeds: Presence of one cotyledon or embryonic leaf.
     Leaves: Veins run parallel.
     Flower parts: Occur in multiples of 3.
     Roots: Fibrous system present.
     Vascular tissues: Scattered in the entire stem.
     Examples: Palm trees, corn, grasses, orchids
  2. Dicots-
     Seeds: Presence of two cotyledon or embryonic leaves.
     Leaves: Veins run in the branched network.
     Flower parts: Occur in a group of 4 or 5.
     Roots: Taproot system.
     Vascular tissues: Tubular arrangement in the stem.
     Examples: Oaks, apple trees, cacti, daisies, sunflowers, coffee
• Gymnosperms
  Here, seeds are not present in the protective covering such as fruit or ovary. They produce both male and female cones. Male cones are pollen, and female is seed cone. Male cone releases pollen which is used to fertilize the seeds on female cone developed on the exposed upper surface.
  Examples: Pines. Redwoods, firs

Plant classification based on habitat

1. Water plants-
   These plants are also known as aquatic plants. The term itself reveals that these plants live underwater.
   
   • Roots: Branched outside and small in size which aids plants in floating inside or on the surface of the water.
   • Leaves: Stomata is present on the top surface of the leaves. Leaves are present under or near the water. Through stomata, aquatic plants have an access to air.
   • Examples: Water caltrop, lotus, water spinach, wild rice
2. Aerial plants-
   These plants grow above the ground and hence the name. They are usually found in rainforests.
   
   • Roots: They are short. They aid in attaching to nearby taller plants.
   • Examples: Orchids, banyan tree, bromeliads
3. Land plants-
   They are also known as terrestrial plants.
   
   • Roots: Stomata is present on the bottom portion of their leaves in contrast to aquatic plants because of the presence of an abundant amount of air to them. Roots length is long to absorb water and minerals from the soil to fulfil the requirement of terrestrial plants.
   • Examples: Mango, bamboo

Plant classification based on life span

1. Ephemerals
   These are the plants that complete their life cycle within the span of a few weeks. The reason for the short life span is because the window of growing is short in their cases as they grow only in certain seasons. They are usually found in cold regions or deserts.
   Examples: Arabidopsis
2. Annuals
   These are the plants that complete their life cycle within the span of 1 year. They germinate from the seed, grow to their full potential, and reproduce by bearing fruits and flowers and dies off. All these take place within a year.
   Examples: Watermelon, grass, corn, rice grass
3. Biennials
   These plants have a life cycle of a span of 2 years. In the first year, their germination, development of root system takes place. Their stem develops and leaves start growing. In the second year, the development of flowers and fruits take place.
   Examples: Carrots, onions, spinach
4. PerennialsThese plants have a life cycle of more than 2 years. Just like any other plant, they germinate, growth takes place by the development of root and shoot system. They bear fruits and flowers. However, they do not die off after bearing fruits. They can renew their parts, and that is what makes them live longer.
   Examples: Coconut tree, ginger, banana, banyan tree

Plant classification based on growth habits

1. Herbs-
   These plants do not have woods. Their stem is soft and small. They are small in size, usually around 1m above the ground. Herbs can be annual, biennial as well as perennial.
   Example: Mint
2. Shrubs-
   These are woody plants. They are longer than herbs but shorter than a tree. Their height may be in the range of 1-4m. Unlike trees, they do not have the main trunk. They usually branch near the base. They develop multiple stems which are covered with leaves and flowers. These plants are usually perennial.
   Example: Rose
3. Trees
   These are thick woody plants. They are taller than shrubs. They develop one main trunk which may or may not develop branches. They are mainly perennial. Some trees do not develop branches. The main trunk itself will develop all the leaves, fruits and flowers.
   Example: Coconut tree
   Some trees develop branches which will bear leaves, fruits and flowers.
   Example: Mango tree
4. Creepers
   These plants have long stems, but they are too thin and fragile to support the plant. Thus, the creepers cannot support themselves, unlike other plants. They cannot wear their weight, and that is the reason they creep on the ground.
   Example: Watermelon
5. Climbers
   Climbers resemble creepers but are their advanced version. Just like creepers, they too have a thin and fragile stem which is very long. They too cannot stand erect and bear their weight. However, they do not creep on the ground. They seek support from external environment and grow vertically. Tendrils are the parts that help them to climb and seek vertical support.
   Example: Money plant