Kingdom Plantae, Division Coniferophyta (Conifers )
General and Distinctive Features of the Division Angiospermophyta
Explain general and distinctive features of the division angiospermophyta
Angiosperms
are flowering plants under kingdom Plantae and division
Angiospermophyta. This group of plants is sometimes called
Magnoliophyta. Angiosperms are the most abundant land plants. Like
gymnosperms, angiosperms are seed-producing plants but they are
distinguished from gymnosperms by their characteristic of producing
flowers. These plants produce fruits that contain seeds instead of cones
like it is in gymnosperms. The term angiosperm means a plant that
produces seeds within fruits.
are flowering plants under kingdom Plantae and division
Angiospermophyta. This group of plants is sometimes called
Magnoliophyta. Angiosperms are the most abundant land plants. Like
gymnosperms, angiosperms are seed-producing plants but they are
distinguished from gymnosperms by their characteristic of producing
flowers. These plants produce fruits that contain seeds instead of cones
like it is in gymnosperms. The term angiosperm means a plant that
produces seeds within fruits.
Angiosperms life cycle:The
ovary has ovules that contain mega-sporocyte. Mega-sporophyte has four
haploid megaspores; three megaspores disintegrate and the remaining one
divides by mitotic divisions to produce eight nuclei in an embryo sac.
The three nuclei are organized into the egg whereby one cell is the egg
cell; the two others are egg helpers. Although these three cells look
are similar, only the egg cell continues to develop to an embryo sac.
The embryo sac at this stage is the female gametophyte or
mega-gametophyte.
ovary has ovules that contain mega-sporocyte. Mega-sporophyte has four
haploid megaspores; three megaspores disintegrate and the remaining one
divides by mitotic divisions to produce eight nuclei in an embryo sac.
The three nuclei are organized into the egg whereby one cell is the egg
cell; the two others are egg helpers. Although these three cells look
are similar, only the egg cell continues to develop to an embryo sac.
The embryo sac at this stage is the female gametophyte or
mega-gametophyte.
Pollination and fertilization:The
pollen from the anther is transported to the stigma of a flower. In the
stigma pollen tube emerges. The mature male gametophyte therefore is a
germinated pollen grain, pollen tube and three sperm nuclei. The pollen
tube grows downward toward the ovary through the style and penetrates
the embryo sac. After discharging its contents one of the sperm nuclei
fuses with the egg nucleus and form a zygote, the other sperm fuses with
the polar cell of the ovary, forming the endosperm nucleus. This is
what is known as double fertilization. Fertilization in angiosperms
begins very soon after pollination.
pollen from the anther is transported to the stigma of a flower. In the
stigma pollen tube emerges. The mature male gametophyte therefore is a
germinated pollen grain, pollen tube and three sperm nuclei. The pollen
tube grows downward toward the ovary through the style and penetrates
the embryo sac. After discharging its contents one of the sperm nuclei
fuses with the egg nucleus and form a zygote, the other sperm fuses with
the polar cell of the ovary, forming the endosperm nucleus. This is
what is known as double fertilization. Fertilization in angiosperms
begins very soon after pollination.
Note: In gymnosperms, fertilization can occur up to a year after pollination.
Double fertilization:Double
fertilization is a distinctive characteristic of the angiosperms and
results in a polyploid endosperm tissue. In double fertilization each
ovule receives a pollen tube that delivers two sperm cells to the embryo
sac. One sperm fertilizes the egg cell to form the diploid zygote,
while the other sperm fertilizes the central polar cell to form triploid
endosperm. After double fertilization, the ovule develops into a seed
and the ovary into a fruit.
fertilization is a distinctive characteristic of the angiosperms and
results in a polyploid endosperm tissue. In double fertilization each
ovule receives a pollen tube that delivers two sperm cells to the embryo
sac. One sperm fertilizes the egg cell to form the diploid zygote,
while the other sperm fertilizes the central polar cell to form triploid
endosperm. After double fertilization, the ovule develops into a seed
and the ovary into a fruit.
General features of angiosperms
They
bear flowers which are reproductive structures. Fertilization takes
place between male and female flower by pollination that includes insect
pollination, wind pollination and animal pollination.
bear flowers which are reproductive structures. Fertilization takes
place between male and female flower by pollination that includes insect
pollination, wind pollination and animal pollination.
- Angiosperms have underground root as well as aerial shoot system.
- Angiosperms
have very well-developed conducting tissues. These tissues include the
xylem and the phloem arranged in form of vascular bundles. - They have root that helps absorption of water and minerals from the soil.
- Most of them have leaves that carry out photosynthesis, so they are autotrophs.
- They
have alternation of generation, Sporophyte generation alternate with
gametophyte generation. The sporophyte is the dominant, diploid stage
and is the more visible form of the plant, with the leaves, stems,
roots, and flowers. Gametophyte generation is reduced and it is found
within the ovary and anther.
Distinctive features of angiosperms
- The most obvious distinguishing feature of angiosperms is the possession of reproductive structures called flowers.
- They bear seeds enclosed in a carpel (the fruit). The seeds are the fertilized ovules.
- They
have endosperm produced after fertilization and before the zygote
undergo its first division. Endosperm has nourishing function, it
nourishes the embryo. - They have double fertilization whereby
each ovule receives a pollen tube that delivers two sperm cells to the
embryo sac. One sperm fertilizes the egg cell to form the diploid
zygote, while the other sperm fertilizes the central polar cell to form
triploid endosperm. - Their haploid gametophyte is confined inside
the ovary (female) or anther (male) of the flower, unlike the free-
living gametophytes of most other plants. - They have conducting tissues phloem and xylem. Unlike gymnosperms which have xylem tracheid angiosperms has xylem vessels.
The Classes of the Division Angiospermophyta and their Distinctive Features
Outline the classes of the division angiospermophyta and their distinctive features
Division
Angiosperms is divided into two classes which are Monocotyledonae and
Dicotyledonae. These two classes are distinguished from each other by
their morphology and anatomy.
Angiosperms is divided into two classes which are Monocotyledonae and
Dicotyledonae. These two classes are distinguished from each other by
their morphology and anatomy.
Features of Class Monocotyledonae
- Monocots have one cotyledon (or one seed leaf)
- Monocots have broad leaves with parallel venation.
- Monocots have fibrous root systems.
- The floral parts in monocots occur in threes, or multiple of three. PMonocots lack cambium secondary growth.
- Monocots have scattered vascular bundles in their stems.Typical example of monocot is a maize plant.
Features of Class Dicotyledonae
- Dicots have two cotyledons (or two seed leaves).
- Dicots have net venation.
- Dicots have tap root system
- Dicots floral parts occur in fours and fives and multiple of four or five.
- Dicots have cambium secondary growth.
- Dicots have vascular bundles arranged into a ring. A Typical example of dicot is a bean plant.
The Structure of Representative Plants Under Each Class (Monocotyledonae and Dicotyledonae)
Describe the structure of representative plants under each class (Monocotyledonae and Dicotyledonae)
Structure ofMonocotyledonae and Dicotyledonae plants
Advantages and Disadvantages of Division Angiospermophyta
Explain advantages and disadvantages of division dngiospermophyta
Advantages of Angiosperms
- Agriculture.
Agriculture depends on angiosperms. Angiosperms provide human food.
Example; plants belonging to grass family (grains), are the most
important food stocks. They include rice, maize, wheat, barley, millet,
sugar cane and sorghum. Legume provides beans, several varieties of nuts
and soy. Also of potatoes, tomatoes, and peppers, pumpkins, melons and
varieties of vegetables to include cabbage and lettuce. Many fruits
oranges, lemons and grapefruits are angiosperms. - Livestock.
Plants belonging to grass family are the world number one feeds of
livestock. Many types of grassland in Africa are either grazed by cattle
or wild animals. Also almost all feeds consumed by human are also used
by domestic animals as food. - Wood. Angiosperms
provide different varieties of wood for furniture, paper and building
materials. Carpentry and masonry depends largely on angiosperms for both
soft and hard wood. - Textile. Different
varieties of fibers including cotton, flax, and hemp are important raw
materials for textile industry. Cotton is the word first class material
for clothes. - Medicine. Many organic drugs are
coming from angiosperm herbs. They are either industrial made or can be
utilized in its raw form. Today it is believed that herbs form the best
medicine when used in their fresh form than when industrial made. - Floriculture.
Flowers from angiosperms have great social significance as they are
used in different kinds of ceremony. Roses for instance are the most
sold flowers and they are highly purchased and used in wedding and
burial ceremonies. - Forestry. Forestry is the
field of study whose base depends on both angiosperms and gymnosperms.
Many forests form green belts that habit different varieties of plants. - Ecology.
Angiosperms provide a wide range of habitats for different species of
organisms. They also serve as primary producers of energy. - Climate. Angiosperms are used to modify climate. Green belts are established in order to absorb carbon and reduce global warming.
- Tourism.
Many sites of tourism are plants oriented. Ecotourism for instance
depends largely on different plant species that host different kinds of
land animals.
Disadvantages of Angiosperms
- Toxins.
Some plants are poisonous when eaten by human and other animals. They
cause death to human and other living organisms. Some cassava varieties
are a good example. They have cyanide acid that inhibits cellular
respiration. - Drugs. Some angiosperm varieties
are drugs that can be abused when taken. Examples are marijuana,
cocaine, tobacco and some caffeine varieties. - Weeds.
Some angiosperm varieties are bad weeds; they reduce crop yields. Some
weeds are parasites. Example, Cuscuta kilimanjari is parasitic to coffee
plantations.
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