Diversity Of Plants

Plants are a large group of living components in nature which has a has stems, leaves, roots, flowers, seeds etc. They are really important for the planet and for all living things. So let us learn about the diversity of plants briefly.

Types of plants

According to the ability of producing flowers plants can be classified into two groups.

1. 1. 1. Flowering plants
      2. Non flowering plants

Flowering plants

Plants which produce flowers are called flowering plants. Rose, ʻIddaʼ, Gardenia, Balsam, Water lily, ʻSalʼ, Lotus, Shoe flower, Curry leaves, Jasmine, Coconut, Long bean are some examples.

Non flowering plants

Plants which do not produce flowers are called non flowering plants. Cycas, Moss, Salvinia, Cyperus, Drynaria, Ferns are some examples.

Main parts of a flowering plant

Observe the flowering plants in your surroundings. They are of different sizes. You will observe small plants as well as big trees among them. Their stems, roots, flowers and fruits are also different from each other. Therefore, plants show a great diversity in their size and morphological features, but all flowering plants have some common parts. They are,

1. 1. Root system
   2. Stem
   3. Lateral buds (Axillary buds)
   4. Leaves
   5. Apical bud
   6. Branches
   7. Fruits
   8. Flowers
   9. Shoot system

Diversity of the parts of flowering plants

Diversity among roots of plants

Normally root system remains underground in the soil. There are two types of root systems.

1. 1. Tap root system
   2. Fibrous root system

Some plants have a single large root which originates from the base of the stem. It is called the tap root. Large number of roots are originated from the tap root. They are called lateral roots. This type of root system is called a tap root system.
e.g.:- ʻKuppameniyaʼ/ ʻKuppaimaniʼ, Mango, Cashew

Some plants have a large number of small roots which are originated from base of the plant stem. This type of root system is called a fibrous root system.
e.g.:- Coconut, Arecanut, Bamboo, Grass, ʻKitulʼ

Functions of roots of plants

• Fix the plant to the soil
• Absorb water and minerals dissolved in water (absorption)
• Give rise to new plants through vegetative propagation
  e.g.:- Curry leaves, ʻBeliʼ/ ʻVilvamʼ, Bread fruit

Roots adapted for various functions

1. Prop roots- Support the branches (Eg:- Banyan)
2. Stilt roots- Support the stem (Eg:- Pandanus)
3. Aerial roots- Absorb water vapor from the atmosphere. Some aerial roots carryout photosynthesis (Eg:- Orchid)
4. Climbing roots- Helps to climb the stem by attaching to another stem (Eg:- Pepper)
5. Respiratory roots- Exchange of air with the atmosphere (Eg:- Pneumatophores)
6. Storage roots- Store food (Eg:- Carrot)
7. Roots with root nodules- Bacteria live inside root nodules add nutrients to the soil. Thus make the soil fertile. (Eg:- Mimosa)

Diversity among stems of plants

You have seen very strong stems, stems with thick bark as well as stems with various colours. There are plants that
grow up with the help of supporters and run on the ground due to their weak stems. The basic difference in any type of the stem is that whether the stem divides into branches or not.

1. 1. Branched stem (Eg:- Mango, Rambutan, Cashew, Guava, Shoe flower)
   2. Unbranched stem (Eg:- Coconut, Arecanut, Kitul, Palmyrah, Paddy, Bamboo)

Functions of plant stem

• Bears flowers, leaves, buds, fruits and seeds.
• Supports the plant, by keeping rigid.
• Transports water and food through plant body
• Many plants produce new plants by stems. (vegetative propagation)
  e.g.:- Shoe flower, Jasmine, Sweet potato, Manioc
• Some plants with green coloured stems carryout photosynthesis
• Some aerial stems store food.
  e.g.:- Sugar cane

Even though most stems grow above the soil, some stems grow inside the soil. They are called underground stems. Some of them are ginger, onion, potato etc.

Diversity among leaves of plants

Plant leaves also display a great diversity similar to other parts of the plant based on shape, size and color. Photosynthesis mainly occurs in a leaf of a plant. Plant leaves get energy from sunlight to do photosynthesis. Therefore, leaves are arranged on the stem in a way to get maximum amount of sunlight.

Leaf Venation

The arrangement of veinlets in the leaf is called leaf venation. There are two main venation patterns occur in plants.

1. Reticulate venation- The branches initiated from the midrib spread as a net through out the leaf (Eg:- Shoe flower, Mango, Jak)
2. Parallel venation- Veinlets parallel to the midrib spread in the leaf.
   (Eg:- Grass, Bamboo, Coconut, Arecanut)

Simple and compound leaves

When the leaf blade of a leaf is not divided into segments it is called a simple leaf.  But the leaf blade of some simple leaves are partially divided into segments.
e.g.:- Manioc, Papaw

Leaf blade of a compound leaf is completely divided into small leaf like parts called leaflets. These types of leaves with leaflets are called compound leaves.
e.g.:- Coconut, Tamarind

Functions of plant leaves

• The main function of a plant leaf is photosynthesis. Through photosynthesis plants produce food in leaves.
• Some leaves are adapted to store water.
• Some leaves produce new plants (vegetative reproduction).

Diversity of flowers

The main function of flowers is to produce fruits. The seeds inside the fruits produce new plants. These seeds are dispersed by various methods (by animals, wind, water, explosive mechanism).

Flowers bear male and female reproductive structures. They combine and form seeds by sexual reproduction. The most attractive part of the plant is the flower. They differ greatly in size, smell, shape and colour.

Flowers show great diversity among them, but they have a common structural plan. A typical flower consists of the following three parts.

1. 1. Sepals
   2. Petals
   3. Gynoecium/ Androecium

Diversity of fruits and seeds

Fruits are formed from the flowers of flowering plants. Seeds are found inside the fruits. They produce new plants. Fruits and seeds are naturally adapted for dispersion. There three main ways of dispersion of fruits. They are,

1. Fruits and seeds which are dispersed by wind (Eg:- Cotton)
2. By animals (Eg:- Tomato, Papaya)
3. By water (Eg:-Lotus, Coconut)

Monocotyledonous and dicotyledonous plants

Flowering plants are mainly divided into two groups as,

1. Monocotyledonous (monocots)
2. Dicotyledonous (dicots)

You may have seen that certain seeds can be divided easily into two seed lobes whereas other seeds cannot be divided easily like that. There are two seed lobes. These seed lobes are called seed leaves (Cotyledons).

Seeds with two cotyledons are called dicot seeds. Some seeds cannot be divided into two seed lobes because they have only one seed leaf (cotyledon). This type of seeds are called monocot seeds. And also germination of monocot and dicot seeds are different from each other.

Let us study the differences of basic parts of monocot plants and dicot plants in our surrounding.

Part	Monocot plant	Dicot plant
Seeds	Only one seed lobe	Two seed lobes
Stem	Not branched	Branched
Leaves	Parallel venation	Reticulate venation
Flowers	Three petals or its multiples	Four/ Five petals or its multiples
Root	Fibrous root system	Tap root system

Now you must have a proper understanding about the vast diversity of members of the plant world by this article. Hope it is useful!!!