Page 67 - Viva ICSE Science 4 : E-book

Shoot System

The shoot system consists of the stems,

leaves, fl owers and fruits. These parts
usually grow above the ground.

Stem is the part of the plant from which

branches, leaves, fl owers and fruits
grow. It can be either strong or weak. For

example, big trees have thick and strong
stem called trunk while herbaceous

plants, climbers and creepers have weak A big tree with a trunk A herb with
weak stems
stems. It can be highly branched in some
plants.

Functions of stem

• It provides strength to the plant to stand straight and upright.

• It carries water and minerals from the roots to the leaves for making food.

• It carries food from the leaves to various parts of the plant.

• It also stores food in some plants like potato, ginger and sugar cane. These stems
are eaten by us.

Leaves are called the food factories of green plants as they

prepare food for the plant by the process of photosynthesis. midrib
veins
They diff er greatly in size, shape and colour. We have already
base lamina
read about the structure of a leaf in the previous class. Let’s petiole
stem
review it quickly.
Structure of a leaf

Leaf blade or lamina is the fl at and broad part of a leaf. The part that links the leaf to the

stem is called petiole. A central vein, called the main vein (midrib), runs from the petiole
to the leaf’s tip and divides it into two equal parts. A number of tiny channels called

veins, run all over the surface of a leaf. Veins form a network to carry water and minerals
to all parts of the leaf. A number of small openings called stomata, present on the under

surface of a leaf help in the exchange of gases (breathing).

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