The characteristic feature of the flowering plant is formation of flowers. Almost all parts such as stem, leaves, roots, buds, flowers and fruits can be seen in most of the plants. Plants show a great diversity among these parts.
Diversity among roots of plants
Normally root system remains underground in the soil.
There are two types of root systems.
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 ²
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
In addition there are some roots adapted for different functions. Let's do Assignment 1.4 to identify such roots.
storage roots
different types of roots
Diversity among stems
The basic difference in any type of the stem is that whether the stem divides into branches or not.
Functions of plant stem
1. Bears flowers, leaves, buds, fruits and seeds.
2.Supports the plant, by keeping rigid.
3.Transports water and food through plant body
4.Many plants produce new plants by stems. (vegetative propogation) e.g.:- Shoe flower, Jasmine/ 'Saman pichcha' / 'Sadimalligai', Sweet potato, Manioc
5. Some plants with green coloured stems carryout photosynthesis e.g.:- ʻNawahandiʼ / ʻKallyʼ, ʻHeeressaʼ / ʻPirattaiʼ, ʻHathawariyaʼ/ ʻSathavariʼ
6.Some aerial stems store food. e.g.:- Sugar cane, Kitul
underground stems.
Even though most stems grow above the soil, some stems grow inside the soil. They are called underground stems.
Diversity of leaves
Leaf venation
The arrangement of veinlets in the leaf is called leaf venation. There are two main venation patterns occur in plants.
Simple and compound leaves
simple leaf.
leaf blade of a leaf is not divided into segments it is called.
e.g.:- Shoe flower, Jak The leaf blade of some simple leaves are partially divided into segments. e.g.:- Manioc, Papaw
e.g.:- Coconut, ʻKaturumurungaʼ/ ʻAgathiʼ, Tamarind
compound leaves.Leaf blade of a compound leaf is completly divided into small leaf like parts called leaflets. These types of leaves with leaflets are called compound leaves
. e.g.:- Coconut, ʻKaturumurungaʼ/ ʻAgathiʼ, 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. e.g.:- Aloe, ʻAkkapanaʼ / ʻSadaikaraichchanʼ
* Some leaves produce new plants (vegetative reproduction). e.g.:- ʻAkkapanaʼ, Begonia
Parts of a flower and diversity of flowers
a common structural plan. A typical flower consists of the following three parts.
1.Sepals
2.Petals
3.Gynoecium/ Androecium
Sepals Sepals
are generally green in colour. The main function of sepals is the protection of flower buds.
Petals
Petals are brightly coloured. They attract insects for pollination as well as protect the internal parts of the flower.
Androecium
The male part of a flower is called androecium which consists of stamen. Each stamen is made up of two parts.
*anther
*filament
The function of androecium is production of pollen. Different shapes of stamens can be seen in flowers
Gynoecium contains following parts. ²
*Stigma
* Style
*Ovary
Ovules are present within the ovary. The function of gynoecium is the production of seeds.
Diversity of fruits and seeds
Fruits are formed from the flowers of flowering plants. Seeds are found inside the fruits. Seeds produce new plants
*Wind
*Water
*Animal
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