Based on the position of the calyx, corolla, and androecium (with respect to the ovary on the thalamus), the flowers are described as hypognous, perigynous, and epigynous. In hypogynous flowers, the ovary occupies the highest position on the thalamus while other floral parts are situated below it. IRead more
Based on the position of the calyx, corolla, and androecium (with respect to the ovary on the thalamus), the flowers are described as hypognous, perigynous, and epigynous.
In hypogynous flowers, the ovary occupies the highest position on the thalamus while other floral parts are situated below it. In such flowers, the ovary is superior
e.g., China rose, mustard etc.
In perigynous flowers, the ovary is situated at the centre and other floral parts are arranged on the rim of the thalamus. The ovary here is said to be half inferior e.g., plum, rose, peach
In epigynous flowers, the thalamus grows around the ovary fusing with its wall. The other floral parts are present above the ovary. Hence, the ovary is said to be inferior
e.g., flowers of guava and cucumber.
Inflorescence is the manner in which the flowers are arranged on the flowering axis. During the flowering season, the vegetative apex of the stem gets converted into a floral meristem. Based on whether the floral axis continues to grow or end in a flower, inflorescence is classified into racemose anRead more
Inflorescence is the manner in which the flowers are arranged on the flowering axis. During the flowering season, the vegetative apex of the stem gets converted into a floral meristem. Based on whether the floral axis continues to grow or end in a flower, inflorescence is classified into racemose and cymose. In racemose inflorescence, the floral axis continues to grow and produces flowers laterally. On the other hand, in cymose inflorescence, the main axis terminates into a flower. Hence, it is limited in growth.
The main function of the leaves is to carry out the process of photosynthesis. However, in a few plants, leaves are modified to perform different functions. (a) Tendrils: The leaves of a pea plant are modified into tendrils that help the plant in climbing. (b) Spines: The leaves in cactus are modifiRead more
The main function of the leaves is to carry out the process of photosynthesis. However, in a few plants, leaves are modified to perform different functions.
(a) Tendrils: The leaves of a pea plant are modified into tendrils that help the plant in climbing.
(b) Spines: The leaves in cactus are modified into sharp spines that act as an organ of defence.
(c) Phyllode: The leaves of some Australian acacia are short-lived and soon replaced by flattened, green structures called phyllodes that arise from the petiole of the leaves. The petioles in these plants synthesize food.
(d) Pitcher: The leaves of the pitcher plant are modified into pitcher-like structures, which contain digestive juices and help in trapping and digesting insects.
A flower can be defined as the reproductive unit of any flowering plant (angiosperms). Flowers carry out sexual reproduction in angiosperms. A typical flower is a modified stem with a condensed axis. A flower has four different parts i.e., the calyx, corolla, androecium, and gynoecium. Androecium anRead more
A flower can be defined as the reproductive unit of any flowering plant (angiosperms). Flowers carry out sexual reproduction in angiosperms. A typical flower is a modified stem with a condensed axis. A flower has four different parts i.e., the calyx, corolla, androecium, and gynoecium. Androecium and gynoecium represent the male and female reproductive organs of a flower (respectively). Bisexual flowers are those which contain both androecium and gynoecium, while unisexual flowers contain either gynoecium or androecium. The corolla and the calyx are generally distinct, but may sometimes be fused (called perianth). A flower that contains all four floral parts is called a complete flower.
Parts of flowers
(A) The calyx forms the outermost whorl of a flower, which contains sepals. They are green, leaf–like structures that cover and protect the flowers during the bud stage. When the sepals of a flower are free, they are called polysepalous, while fused sepals of a flower are called gamosepalous.
(B) The corolla of a flower is a layer that lies inside the calyx. It contains beautifully coloured petals, which help in attracting insects for pollination. When the petals are free, they are called polypetalous, while fused petals are called gamopetalous.
(C) The androecium or the stamen is the male reproductive part of a flower. It consists of two parts, the filament and the bilobed anther. The bilobed anther is the site for meiosis and the generation of pollen grains.
(D) Gynoecium represents the female reproductive part of a flower. It consists of an ovary. The ovary is connected by a long tube (called style) to the stigma. The ovary bears numerous ovules attached to the placenta.
Stems of various plants have undergone modifications to perform different functions. Underground stems or storage stems: Examples: Rhizomes, Corms, tubers In ginger and banana, the underground stem is called a rhizome. The underground stem in Colocasia (arvi) is known as corm. Rhizomes and corms areRead more
Stems of various plants have undergone modifications to perform different functions.
Underground stems or storage stems:
Examples: Rhizomes, Corms, tubers
In ginger and banana, the underground stem is called a rhizome. The underground stem in Colocasia (arvi) is known as corm. Rhizomes and corms are underground stems, modified for the storage of food. Also, these stems help in vegetative reproduction of these plants. The tips of the underground stem in potato plants become swollen due to the accumulation of food. The potato is a tuber that helps in the storage of food and bears eyes on it. Subtended by a leaf scar, these eyes bear buds that give rise to new plants.
Supportive stems
Example: tendril
The stem in some weak plants bear thin, slender, and spirally-coiled structures called tendrils that help the plant get attached to nearby structures for support. Tendrils are found in cucumbers, melons, and other members of the family Cucurbitaceae.
Protective stems
Example: Thorns
The stem in bougainvillea and citrus plants (like lemon and orange) bear sharp, pointed structures called thorns, which provide protection to the plant from herbivores.
Photosynthetic stems
Example: Opuntia
The stem in the Opuntia is green. It carries out the process of photosynthesis in the absence of leaves.
Others stem modifications
In some plants, underground stems such as grasses spread in the soil and help in perenation. These stems are called runners.
The short lateral stem called the offset in some aquatic plants (such as Eichhornia) bears leaves and tufts of roots at the node and gives rise to new plants.
1. Racemose and cymose inflorescence:- Racemose Inflorescence:- 1. Younger flowers are present at the tip while older flowers are arranged at the base of this inflorescence. Such an arrangement is called acropetal succession. 2. The main axis in racemose inflorescence continues to grow and produce fRead more
1. Racemose and cymose inflorescence:-
Racemose Inflorescence:-
1. Younger flowers are present at the tip while older flowers are arranged at the base of this inflorescence. Such an arrangement is called acropetal succession.
2. The main axis in racemose inflorescence continues to grow and produce flowers laterally.
Cymose Inflorescence:-
(1) Younger flowers are present at the base of the inflorescence, while older flowers are present at the top. Such an arrangement is called basipetal succession.
(2) The main axis in cymose inflorescence has limited growth, which later terminates into a flower.
(b) Fibrous roots and adventitious roots:-
Fibrous root:-
(1) In monocots, the primary root which develops from the radicle of the seed is short-lived and is replaced by a large number of roots arising from the base of the stem.
(2) It is found in wheat and other cereals
Adventitious root:-
(1) These roots arise from any part of the plant other than the radicle of seeds.
(2) It is found in banyan, Monstera, and other plants.
(c) Apocarpous and syncarpous ovary:-
Apocarpous ovary:-
(1) The flowers with apocarpus ovary have more than one carpel. These carpels are free.
(2) It is found in lotus and rose flowers.
Syncarpous ovary:-
(1) The flowers with syncarpous ovary have more than one carpel. However, these carpels are fused.
(2) It is found in the flowers of tomato and mustard.
(a) Aestivation The term ‘aestivation’ refers to the mode in which sepals or petals are arranged in a floral bud with respect to other floral members. There are four types of aestivation in plants i.e., valvate, twisted, imbricate, and vexillary. (b) Placentation The term ‘placentation’ refers to thRead more
(a) Aestivation
The term ‘aestivation’ refers to the mode in which sepals or petals are arranged in a floral bud with respect to other floral members. There are four types of aestivation in plants i.e., valvate, twisted, imbricate, and vexillary.
(b) Placentation
The term ‘placentation’ refers to the arrangement of ovules within the ovary of a flower. It is primarily of five types, namely marginal, basal, parietal, axile, and free central.
(c) Actinomorphic
Actinomorphic flowers can be divided into two radial halves by any radial plane passing through its centre. Examples of these flowers include chilly and mustard.
(d) Zygomorphic
Zygomorphic flowers are those flowers which can be divided into two similar halves by a single vertical plane. Examples of these flowers include pea and beans.
(e) Superior ovary
Superior ovary flowers are those flowers in which the gynoecium is present at the highest position, while other floral parts are arranged below it. A flower with this arrangement is described as hypogynous. Examples include brinjal and mustard.
(f) Perigynous flower
In perigynous flowers, the gynoecium is present in the centre and the rest of the floral parts are arranged at the rim of the thalamus at the same level. Examples include plum and rose.
(g) Epipetalous Stamen
Epipetalous stamens are stamens attached to the petals. They are found in brinjal.
Phyllotaxy refers to the pattern or arrangement of leaves on the stem or branch of a plant. It is of three types, alternate, opposite, and whorled phyllotaxy. In alternate phyllotaxy, a single leaf arises from the node of a branch. This type of phyllotaxy is observed in the sunflower, mustard, and pRead more
Phyllotaxy refers to the pattern or arrangement of leaves on the stem or branch of a plant. It is of three types, alternate, opposite, and whorled phyllotaxy.
In alternate phyllotaxy, a single leaf arises from the node of a branch. This type of phyllotaxy is observed in the sunflower, mustard, and peepal. Plants with opposite phyllotaxy have two leaves arising from the node in opposite directions. It is found in guava and jamun plants. Plants with whorled phyllotaxy have three or more leaves arising from the node. It is found in Alstonia.
Pinnately Compound Leaf:- 1. The leaflets are attached to the common axis, called rachis. 2. Examples include neem and Cassia fistula( also called golden shower plant) Palmately Compound Leaf:- 1. The leaflets are attached at a common point on the leaf stalk. 2. Examples include silk cotton (Bombax)Read more
Pinnately Compound Leaf:-
1. The leaflets are attached to the common axis, called rachis.
2. Examples include neem and Cassia fistula( also called golden shower plant)
Palmately Compound Leaf:-
1. The leaflets are attached at a common point on the leaf stalk.
2. Examples include silk cotton (Bombax) and Cannabis.
(i) Various parts of plants are modified into underground structures to perform various functions such as stems, leaves, and even fruits. The stems in ginger and banana are underground and swollen due to storage of food. They are called rhizomes. Similarly, corm is an underground stem in Colocasia aRead more
(i) Various parts of plants are modified into underground structures to perform various functions such as stems, leaves, and even fruits.
The stems in ginger and banana are underground and swollen due to storage of food. They are called rhizomes. Similarly, corm is an underground stem in Colocasia and Zamin-khand. The tips of the underground stem in potato become swollen due to the accumulation of food and forms tuber. Tubers bear eyes, which are subtended by a leaf scar. Basal leaves in onions become fleshy because of the accumulation of food. In peanuts, the flower after fertilization gets pushed inside the soil by growing a flower stalk. The formation of fruits and seeds takes place inside the soil.
(ii) During the flowering season, the apical meristem gives rise to the floral meristem. The axis of the stem gets condensed, while the internodes lie near each other. Instead of leaves, various floral appendages arise from the node. Therefore, it can be said that the flower is a modified shoot.
Describe the arrangement of floral members in relation to their insertion on thalamus?
Based on the position of the calyx, corolla, and androecium (with respect to the ovary on the thalamus), the flowers are described as hypognous, perigynous, and epigynous. In hypogynous flowers, the ovary occupies the highest position on the thalamus while other floral parts are situated below it. IRead more
Based on the position of the calyx, corolla, and androecium (with respect to the ovary on the thalamus), the flowers are described as hypognous, perigynous, and epigynous.
In hypogynous flowers, the ovary occupies the highest position on the thalamus while other floral parts are situated below it. In such flowers, the ovary is superior
e.g., China rose, mustard etc.
In perigynous flowers, the ovary is situated at the centre and other floral parts are arranged on the rim of the thalamus. The ovary here is said to be half inferior e.g., plum, rose, peach
In epigynous flowers, the thalamus grows around the ovary fusing with its wall. The other floral parts are present above the ovary. Hence, the ovary is said to be inferior
e.g., flowers of guava and cucumber.
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Define the term inflorescence. Explain the basis for the different types of inflorescence in flowering plants.
Inflorescence is the manner in which the flowers are arranged on the flowering axis. During the flowering season, the vegetative apex of the stem gets converted into a floral meristem. Based on whether the floral axis continues to grow or end in a flower, inflorescence is classified into racemose anRead more
Inflorescence is the manner in which the flowers are arranged on the flowering axis. During the flowering season, the vegetative apex of the stem gets converted into a floral meristem. Based on whether the floral axis continues to grow or end in a flower, inflorescence is classified into racemose and cymose. In racemose inflorescence, the floral axis continues to grow and produces flowers laterally. On the other hand, in cymose inflorescence, the main axis terminates into a flower. Hence, it is limited in growth.
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How do the various leaf modifications help plants?
The main function of the leaves is to carry out the process of photosynthesis. However, in a few plants, leaves are modified to perform different functions. (a) Tendrils: The leaves of a pea plant are modified into tendrils that help the plant in climbing. (b) Spines: The leaves in cactus are modifiRead more
The main function of the leaves is to carry out the process of photosynthesis. However, in a few plants, leaves are modified to perform different functions.
(a) Tendrils: The leaves of a pea plant are modified into tendrils that help the plant in climbing.
(b) Spines: The leaves in cactus are modified into sharp spines that act as an organ of defence.
(c) Phyllode: The leaves of some Australian acacia are short-lived and soon replaced by flattened, green structures called phyllodes that arise from the petiole of the leaves. The petioles in these plants synthesize food.
(d) Pitcher: The leaves of the pitcher plant are modified into pitcher-like structures, which contain digestive juices and help in trapping and digesting insects.
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What is a flower? Describe the parts of a typical angiosperm flower?
A flower can be defined as the reproductive unit of any flowering plant (angiosperms). Flowers carry out sexual reproduction in angiosperms. A typical flower is a modified stem with a condensed axis. A flower has four different parts i.e., the calyx, corolla, androecium, and gynoecium. Androecium anRead more
A flower can be defined as the reproductive unit of any flowering plant (angiosperms). Flowers carry out sexual reproduction in angiosperms. A typical flower is a modified stem with a condensed axis. A flower has four different parts i.e., the calyx, corolla, androecium, and gynoecium. Androecium and gynoecium represent the male and female reproductive organs of a flower (respectively). Bisexual flowers are those which contain both androecium and gynoecium, while unisexual flowers contain either gynoecium or androecium. The corolla and the calyx are generally distinct, but may sometimes be fused (called perianth). A flower that contains all four floral parts is called a complete flower.
Parts of flowers
(A) The calyx forms the outermost whorl of a flower, which contains sepals. They are green, leaf–like structures that cover and protect the flowers during the bud stage. When the sepals of a flower are free, they are called polysepalous, while fused sepals of a flower are called gamosepalous.
(B) The corolla of a flower is a layer that lies inside the calyx. It contains beautifully coloured petals, which help in attracting insects for pollination. When the petals are free, they are called polypetalous, while fused petals are called gamopetalous.
(C) The androecium or the stamen is the male reproductive part of a flower. It consists of two parts, the filament and the bilobed anther. The bilobed anther is the site for meiosis and the generation of pollen grains.
(D) Gynoecium represents the female reproductive part of a flower. It consists of an ovary. The ovary is connected by a long tube (called style) to the stigma. The ovary bears numerous ovules attached to the placenta.
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Describe modifications of stem with suitable examples
Stems of various plants have undergone modifications to perform different functions. Underground stems or storage stems: Examples: Rhizomes, Corms, tubers In ginger and banana, the underground stem is called a rhizome. The underground stem in Colocasia (arvi) is known as corm. Rhizomes and corms areRead more
Stems of various plants have undergone modifications to perform different functions.
See lessUnderground stems or storage stems:
Examples: Rhizomes, Corms, tubers
In ginger and banana, the underground stem is called a rhizome. The underground stem in Colocasia (arvi) is known as corm. Rhizomes and corms are underground stems, modified for the storage of food. Also, these stems help in vegetative reproduction of these plants. The tips of the underground stem in potato plants become swollen due to the accumulation of food. The potato is a tuber that helps in the storage of food and bears eyes on it. Subtended by a leaf scar, these eyes bear buds that give rise to new plants.
Supportive stems
Example: tendril
The stem in some weak plants bear thin, slender, and spirally-coiled structures called tendrils that help the plant get attached to nearby structures for support. Tendrils are found in cucumbers, melons, and other members of the family Cucurbitaceae.
Protective stems
Example: Thorns
The stem in bougainvillea and citrus plants (like lemon and orange) bear sharp, pointed structures called thorns, which provide protection to the plant from herbivores.
Photosynthetic stems
Example: Opuntia
The stem in the Opuntia is green. It carries out the process of photosynthesis in the absence of leaves.
Others stem modifications
In some plants, underground stems such as grasses spread in the soil and help in perenation. These stems are called runners.
The short lateral stem called the offset in some aquatic plants (such as Eichhornia) bears leaves and tufts of roots at the node and gives rise to new plants.
Differentiate between: (a) Racemose and cymose inflorescence (b) Fibrous roots and adventitious roots (c) Apocarpous and syncarpous ovary
1. Racemose and cymose inflorescence:- Racemose Inflorescence:- 1. Younger flowers are present at the tip while older flowers are arranged at the base of this inflorescence. Such an arrangement is called acropetal succession. 2. The main axis in racemose inflorescence continues to grow and produce fRead more
1. Racemose and cymose inflorescence:-
Racemose Inflorescence:-
1. Younger flowers are present at the tip while older flowers are arranged at the base of this inflorescence. Such an arrangement is called acropetal succession.
2. The main axis in racemose inflorescence continues to grow and produce flowers laterally.
Cymose Inflorescence:-
(1) Younger flowers are present at the base of the inflorescence, while older flowers are present at the top. Such an arrangement is called basipetal succession.
(2) The main axis in cymose inflorescence has limited growth, which later terminates into a flower.
(b) Fibrous roots and adventitious roots:-
Fibrous root:-
(1) In monocots, the primary root which develops from the radicle of the seed is short-lived and is replaced by a large number of roots arising from the base of the stem.
(2) It is found in wheat and other cereals
Adventitious root:-
(1) These roots arise from any part of the plant other than the radicle of seeds.
(2) It is found in banyan, Monstera, and other plants.
(c) Apocarpous and syncarpous ovary:-
Apocarpous ovary:-
(1) The flowers with apocarpus ovary have more than one carpel. These carpels are free.
(2) It is found in lotus and rose flowers.
Syncarpous ovary:-
(1) The flowers with syncarpous ovary have more than one carpel. However, these carpels are fused.
(2) It is found in the flowers of tomato and mustard.
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Define the following terms: (a) Aestivation (b) Placentation (c) Actinomorphic (d) Zygomorphic (e) Superior ovary (f) Perigynous flower (g) Epipetalous Stamen
(a) Aestivation The term ‘aestivation’ refers to the mode in which sepals or petals are arranged in a floral bud with respect to other floral members. There are four types of aestivation in plants i.e., valvate, twisted, imbricate, and vexillary. (b) Placentation The term ‘placentation’ refers to thRead more
(a) Aestivation
The term ‘aestivation’ refers to the mode in which sepals or petals are arranged in a floral bud with respect to other floral members. There are four types of aestivation in plants i.e., valvate, twisted, imbricate, and vexillary.
(b) Placentation
The term ‘placentation’ refers to the arrangement of ovules within the ovary of a flower. It is primarily of five types, namely marginal, basal, parietal, axile, and free central.
(c) Actinomorphic
Actinomorphic flowers can be divided into two radial halves by any radial plane passing through its centre. Examples of these flowers include chilly and mustard.
(d) Zygomorphic
Zygomorphic flowers are those flowers which can be divided into two similar halves by a single vertical plane. Examples of these flowers include pea and beans.
(e) Superior ovary
Superior ovary flowers are those flowers in which the gynoecium is present at the highest position, while other floral parts are arranged below it. A flower with this arrangement is described as hypogynous. Examples include brinjal and mustard.
(f) Perigynous flower
In perigynous flowers, the gynoecium is present in the centre and the rest of the floral parts are arranged at the rim of the thalamus at the same level. Examples include plum and rose.
(g) Epipetalous Stamen
Epipetalous stamens are stamens attached to the petals. They are found in brinjal.
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Explain with suitable examples the different types of phyllotaxy?
Phyllotaxy refers to the pattern or arrangement of leaves on the stem or branch of a plant. It is of three types, alternate, opposite, and whorled phyllotaxy. In alternate phyllotaxy, a single leaf arises from the node of a branch. This type of phyllotaxy is observed in the sunflower, mustard, and pRead more
Phyllotaxy refers to the pattern or arrangement of leaves on the stem or branch of a plant. It is of three types, alternate, opposite, and whorled phyllotaxy.
In alternate phyllotaxy, a single leaf arises from the node of a branch. This type of phyllotaxy is observed in the sunflower, mustard, and peepal. Plants with opposite phyllotaxy have two leaves arising from the node in opposite directions. It is found in guava and jamun plants. Plants with whorled phyllotaxy have three or more leaves arising from the node. It is found in Alstonia.
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How is pinnately compound leaf different from palmately compound leaf?
Pinnately Compound Leaf:- 1. The leaflets are attached to the common axis, called rachis. 2. Examples include neem and Cassia fistula( also called golden shower plant) Palmately Compound Leaf:- 1. The leaflets are attached at a common point on the leaf stalk. 2. Examples include silk cotton (Bombax)Read more
Pinnately Compound Leaf:-
1. The leaflets are attached to the common axis, called rachis.
2. Examples include neem and Cassia fistula( also called golden shower plant)
Palmately Compound Leaf:-
1. The leaflets are attached at a common point on the leaf stalk.
2. Examples include silk cotton (Bombax) and Cannabis.
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Justify the following statements on the basis of external features (i) Underground parts of a plant are not always roots (ii) Flower is a modified shoot
(i) Various parts of plants are modified into underground structures to perform various functions such as stems, leaves, and even fruits. The stems in ginger and banana are underground and swollen due to storage of food. They are called rhizomes. Similarly, corm is an underground stem in Colocasia aRead more
(i) Various parts of plants are modified into underground structures to perform various functions such as stems, leaves, and even fruits.
The stems in ginger and banana are underground and swollen due to storage of food. They are called rhizomes. Similarly, corm is an underground stem in Colocasia and Zamin-khand. The tips of the underground stem in potato become swollen due to the accumulation of food and forms tuber. Tubers bear eyes, which are subtended by a leaf scar. Basal leaves in onions become fleshy because of the accumulation of food. In peanuts, the flower after fertilization gets pushed inside the soil by growing a flower stalk. The formation of fruits and seeds takes place inside the soil.
(ii) During the flowering season, the apical meristem gives rise to the floral meristem. The axis of the stem gets condensed, while the internodes lie near each other. Instead of leaves, various floral appendages arise from the node. Therefore, it can be said that the flower is a modified shoot.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-5/