SUBJECT:AGRICULTURAL
SCIENCE
WEEK: FOUR
CLASS: GRADE
7
TOPIC: PLANT FORMS AND DISTRIBUTION
PARTS OF CROP PLANT
Two main parts of crop
plants are the shoot and the root. The shoot consists of all parts of the plant
above the ground, which include the leaves, stem, branches, buds, flowers and
fruits, while the root is the part of the plant below the ground. The organs of
the plant can be divided into two:
a.
Vegetative organs: This includes the root, stem and leaves.
b.
Reproductive organs: This includes flowers and fruits.
Root system: The
functions of roots are to anchor the plants to the soil, absorb mineral water
and mineral salts from the soil and in some plants they serve as storage
organs, for example, onions, potatoes and cassava. There are two types of root
systems;
a.
Tap-root system
b.
Fibrous root system
In
a tap root system, there is one major root from which various branches or
lateral roots arise. A fibrous root system consists of similar fine roots all
of which grow from the base of the plant stem.
Stem: The
stem bears the leaves, buds, flowers and fruits. Its functions include support
to the leaves, flowers and fruits. It also transport water and nutrients from
the soil and sugar from the leaves.
Leaves: A
typical leaf consists of a stalk called a petiole and a blade called the
lamina. They contain a very special substance called chlorophyll, which helps
in manufacturing food for plants in the presence of sunlight, through a process
called photosynthesis.
Flower: The
flower is the reproductive part of flowering plants. It is the region where the
male and female organs produce the pollen grain and ovary respectively.
MONOCOTYLEDON AND
DICOTYLEDON
A
crop is any cultivated plant, fungus, or alga that is harvested for food,
clothing, livestock fodder, biofuel, medicine or other uses. Crop plant can
exist in the forms below:
(a) Monocotyledons
These
are crop plants which usually have long, narrow leaves. They include certain
families of grasses, lilies, and orchids. The commonly found trees in this
group are the palms, namely, oil palm, coconut palm, royal palm and raffia
palm. Food crops in this group of plants include rice, wheat, rnillet, maize
and guinea Corn. Sugarcane is an industrial crop which belongs to the same
group.
(b) Dicotyledons
Crop
plants in this group usually have broad leaves. They include most trees such as
the silk cotton, iroko, kola, mango, grapefruit, pawpaw and guava trees. Food
crops in the group include most vegetables, for example, sokoyokoto (Gelosia
argenta), okro, ewedu, water leaf (Talinum triangulare), as well as sweet
potatoes, melon, cowpeas and yam. Industrial crops in the group include cocoa,
cashew and cotton.
ASSIGNMENT
1.
Write short notes on.
a.
Monocotyledon crop.
b.
Dicotyledon crop.
2.
List five crops that are monocotyledons and five crops that are dicotyledons.
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