Angiosperms, the flowering plants. Read about angiosperms, their evolution, classification and their types

1. Angiosperms, the Flowering Plants
Introduction to Angiosperms
The flowering plants or angiosperms are included in the phylum Anthophyta.
They are vascular plants which produce seeds contained in fruits that develop
from parts of reproductive structures called flowers. This group of plants is
the dominant form of plant life on the planet. Members of the phylum are the
source of most of the food on which humans and other mammals rely and of
many raw materials and natural products.
The plants, which are included in the phylum, are most shrubs and herbs,
most familiar trees except pines and other conifers, and specialized plants
such as succulents, parasites and aquatic types. Although about 260,000
species are known, many remain obscure.
Flowering plants occupy almost every ecological situation and dominate most
natural landscapes. About two-third occur in the tropics, where they are
rapidly being exterminated by the human activities. Only about 1000 species
are of major economic importance, and the bulk of the world’s food supply is
derived from only 15. Many hundreds more could be useful if properly
investigated and developed.
Description
The characteristic feature of angiosperms is
the flower, the function of which is the
reproduction of the plant through the
development of seeds. Flowers are highly
modified shoots made up of four fundamental
parts arranged in separate series, or whorls,
on specialized stem tips. The outer series
consists of the sepals, which are modified
leaves or bracts that are usually green. The
next inner series, the petals, are also modified
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2. Angiosperms, the Flowering Plants
leaves, but they are usually finer textured and are colorful. The third series
consists of the stamens, the pollen-producing male part of the flower. The
inner most series is the carpels, the female structures that produce the seeds.
Carpels are often fused into a structure called the pistil.
The seeds of angiosperms develop in an ovary, a part of the carpel that
surrounds and protects egg-containing ovules. Seeds develop from the ovules
after pollination and fertilization of the eggs.
Parts of the flower
Male Parts
1. Stamen
Stamen is made up of filaments and anther. It
produces and stores pollen grain, the male
germ cells. Number of stamens is usually
same as the number of petals.
2. Anther
Part of the anther that produces and stores
pollen. It is a sac like structure and stays on
the top of a stalk like structure, the filament.
3. Filament
This is the stalk that the anther sits on top of.
Female Parts
1. Stigma
It is the top, flattened part of the female reproductive part
that receives pollen from anther.
2. Style
It is a long stalk like structure between ovary and stigma.
3. Ovary
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3. Angiosperms, the Flowering Plants
Ovary is usually found at the bottom of the flower. It produces seeds
inside and turns into fruit upon ripening.
4. Ovule
Ovule is the part of the ovary that contains female germ cells and
becomes seed after fertilization.
Evolution
The closest relatives of gymnosperms remain a mystery, but the unique
angiosperm flower probably evolved from an extinct gymnosperm group that
had insect pollinated cones combining male and female reproductive parts.
Living gymnosperms are wind-pollinated, but among certain fossil and extant
groups provide evidence of insect pollination in the group. Although insects
facilitate pollination, they also eat ovules, and it is believed that the
development of ovule-enclosing carpel of angiosperms was an adaptation to
protect the ovules. The carpel also provided protection from other harmful
environmental influences, such as dryness, and it allowed reduction in the size
of the ovule, refinement of the process of the pollination, and the development
of the other parts of the flower, all of which improved the chance of successful
reproduction.
Scientific Classification
Angiosperm is the common name for the division Magnoliophyta.
Angiosperms are divided into two classes, the Mangliopsida and Lilopsida,
popularly termed as monocots and dicots, representing separate evolutionary
lines that must have diverged early in the history of the group. The direct
predecessor of angiosperms are thought to have been woody gymnosperms.
Monocots are more advanced than dicots, and they evolved from a primitive
dicot group.
Monocots
Monocots are the plants, which contain only one leaf
or cotyledon in their seed. They are the primary food
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4. Angiosperms, the Flowering Plants
source for the much of the planet, whether we eat them or feed them to the
other animals. Maize and wheat are the common examples of monocots.
The monocots have parallel veins in their leaves. The flower possesses the
petals and sepals in the number of multiple of three. The arrangement of
primary vascular bundles in the stem is scattered.
Dicots
Dicots are the plants with two cotyledons or seed
leaves. Most of our fruits and vegetables are dicots.
Most shrubs, some herbs and some trees are
included in this group.
Dicots have scattered or net like venation. The flowering parts exist in fours or
fives and the arrangement of primary vascular bundles in these plants is in a
ring shape.
Medicinal Uses of Angiosperms
Angiosperms provide many useful medicinal ingredients which are used to
maintain a good health and to treat several disorders. Some important fruits
and their medicinal uses are listed below.
1. Apple
Apple is a nutrient-rich fruit which contains many
useful ingredients and nutrients like Phosphorus and
Iron etc. Apple juice is used as an inflammatory for the
digestive tract. It also decreases the acidity of the
stomach. Apple acts as both anti-diarrheal and
laxative. Its juice helps to dissolve access fats, thus decreasing obesity. It
is also used to treat cough and bronchitis.
Apple decreases the risk of cancer, especially that of digestive tract.
Apple juice is a good skin conditioner. It also reduces the fever and
enhances the hearing ability.
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5. Angiosperms, the Flowering Plants
2. Grapes
Grapes are the source of many essential metals
like cobalt and iron and vitamins like B1, B2, B6
and B12. Its juice has been used to treat
metabolism disorders. Grapes are also beneficial
in treating the disorders of liver, kidney, lungs as
well as cardiovascular problems. This fruit is anti-inflammatory and
laxative.
Grape also helps with nervous disorders, hypertension
and bronchitis. It helps to get rid of anemia and has
been proved to treat tuberculosis.
3. Apricot
Apricot contains vitamin B17 and many other useful nutrients. It
decreases the risk of cancer, boosts the immune system and acts as a
laxative. It has been proved useful in treating anemia. It is also useful in
treating respiratory disorders including cough.
Apricot oil is used to make medicines for the
treatment of skin diseases.
4. Pomegranate
Pomegranate juice is cardio-protective, as it
maintains the level of cholesterol, thus protecting
heart by maintaining the blood pressure in a normal range. It is a good
tonic for heart and also enhances the function of liver and kidneys. It is a
good laxative and also treats the stomach inflammation.
Pomegranate has been proved as anticancer and inhibitor against TB. Its
juice inhibits the replication of viral genomes including herpes simplex
virus. Juice of pomegranate decreases the fever due to its antiseptic
properties. It is also beneficial in diarrhea.
5. Cherry
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6. Angiosperms, the Flowering Plants
Cherry is a remedy for insomnia, arthritis, nausea, depression, headache
and abdominal cramps. It destroys the pathogens which cause diseases,
thus help our immune system to protect us from attack of disease
causing agents.
Cherry is rich in antioxidants, so it prevents cancer and heart diseases. It
is a very good source of fiber and Vitamin C. It improves our memory,
reduces body and muscle pain and also reduces the risk of colon cancer.
6. Pear
Pear enhances the function of kidney and is
beneficial in obesity, hypertension, dropsy,
nephritis, kidney stones and in inflammation
of urine bladder. The juice of pear is
externally applied on the body to reduce pain. It is the source of
vitamins and helps in loss of excess weight.
7. Peach
Peach has antioxidant properties and is helpful in
preventing the cancer. Its ingredients (carotenes) keep
our arteries healthy and also enhance our sight or
vision. They help our skin to fight against sun radiation
and prevent the dryness of the skin.
Peach treats digestive ulcers. It contains an ingredient, the selenium,
which provides protection to the heart. It strengthens our bones and
also enhances the nervous system.
Importance of Angiosperms
Angiosperms are the source of 80% of world’s food. Apart from this, they
provide oxygen to us, as all other plants do. They are
source of many medicines. Angiosperms provide
lumber for construction of buildings and for the
manufacturing of furniture. They provide fuel. The
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7. Angiosperms, the Flowering Plants
plants clean our atmosphere by absorbing greenhouse gases like carbon
dioxide and adding oxygen to it. The large members of the group are the
effective wind breakers. They decrease soil erosion and also provide habitat
for many organisms.
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