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Classification of Plants

Biology | 12-14 yrs | Interactive

How are plants classified?

Plants are autotrophs and can make their own food through photosynthesis. Plants are classified based on their genetic and evolutionary relationship and form one of the five major kingdoms of classification.

Who came up with the classification system of organisms?

Carl Linnaeus, father of taxonomy is credited with creating the current system of classification of organisms in use today. In classification, the binomial nomenclature system is used and is in Latin.

It is divided into :

  • Kingdom
  • Division
  • Classification Order
  • Family
  • Genus
  • Species

What are the two main groups of plant classification?

Plants are classified into two main groups. This is a very basic way of classifying them.

I. Non Vascular Plants

  • Non vascular plants are known or thought to be the earliest living plants on the planet. They lack vascular tissues and wood that can give them structural support. They also lack true leaves, stem and roots that can help them transport water and nutrients. Because of this they are limited to a narrow range of habitats. The most common type of non vascular plants include the phylum Bryophyta.
  • The Phylum Bryophyta is a diverse group with over 10,000 plant species and consists of mosses, liverworts and hornworts.
  • Despite lacking some essential plant organs, bryophytes play an important role in minimising erosion along water bodies, carrying out water and nutrient cycling in forests and regulating temperature in permafrosts.
  • They reproduce through spores.

II. Vascular Plants

  • Vascular plants posses vascular tissue (xylem and phloem) that help them to transport water and minerals. They are also known as tracheophytes.

Vascular plants are divided into three main Phylum :

1. Pteridophytes

This phylum consists of over 12,000 species and over two thirds of them are tropical and consist of species of ferns and fern allies.

  • Pteridophytes are seedless plants. They reproduce using spores on the underside of their leaves. These are known as sporophylls. They do not flower or have seeds or cones for reproduction.
  • Pteridophytes have horizontal stems called rhizomes and simple leaves roots. The leaves are called fronds and unroll at maturity.
  • Pteridophytes have adapted to a wide range of habitat. They can be aquatic terrestrial and even cold resistant, but thrive in tropical regions.

2. Gymnosperms

Gymnosperms are thought to be some of the oldest living plants on the planet and exist in temperate and arctic regions. Members of this Phylum include pines, hemlocks, firs and spruce. The name gymnosperms means naked seed, which is exhibited by the presence of cones (or strobili) instead of seeds.

  • Gymnosperms are characterised by wood and green, needle like foliage.
  • Gymnosperms are considered to be heterosporous, that is they produce both male cones and female cones.

3. Angiosperms

Angiosperms are referred to as the flowering plants and is the most diverse Phylum with over 300,000 species, including trees, herbs, shrubs, bulbs, epiphytes(parasitic plants) and plants living in both marine and fresh water habitats.

  • Angiosperms are vascular seed plants, in which the ovule (egg) is fertilised and develops into a seed in an enclosed ovary.
  • The flower carry either the male reproductive system or the female or both.
  • The angiosperms have a very complex vascular tissue system and have adapted themselves to almost all types of temperatures and regions. They have developed extensive root systems and leaves that help them to absorb nutrients and make food for themselves.
  • Angiosperms have localised regions for plant growth called meristems and cambia. These two regions experience cell division for the regeneration or repair of a plant.
  • Angiosperms maybe either monocot or dicots.

What is the difference between monocot and dicot plants?

Monocotyledons

Dicotyledons

1.

Monocotyledons or monocots have one cotyledon embryo.

Dicotyledons have two cotyledons embryo.

2.

The veins in the leaf are parallel

The veins in the leaf are netlike(reticulated)

3.

The vascular tissue bundles are arranged in a complex way.

The vascular tissue bundles are arranged in a ring.

4.

Fibrous root system

Deep tap root system

5.

Flowers parts in multiples of three

Flower parts in multiples of four or five.

6.

Pollen with a single pore

Pollen with three pores

7.

Secondary growth absent

Secondary growth present.

Examples of Monocotyledons

Banana, Orchid, Palm Tree, Sugar cane, Ginger, Onion, Rice, Wheat, Corn, Barley

Examples of Dicotyledons

Mangoes, Almonds, Beans, Peas, Pepper