· Father of plant anatomy is N. Grew.
· Nageli is regarded as the father of modern plant anatomy.
· Safranin and hematoxylin: Safranin stains lignified elements deep red. Eg; sclerenchyma; and hematoxylin stains cellulose elements purple. Eg; living cells like parenchyma.
· Maceration: separation of tissue into its component cells.
· Conc HNO3 + KClO3 (Crystal) is used to loosen the middle lamella between the cells. During the preparation of the permanent slides, sections are kept in different grades of alcohol for dehydration.
· Conc HNO3 + KClO3 (Crystal) is used to loosen the middle lamella between the cells. During the preparation of the permanent slides, sections are kept in different grades of alcohol for dehydration.
A. Tissue:
· Term was coined by N. grew· Defined as a group of similar or dissimilar cells having a common origin and performing a common function.
· Anatomically plant is made up of various types of tissue with specific functions.
· Depending upon the nature of tissue, plant tissue is divided into
1. Meristematic tissue
2. Permanent tissue
3. Special tissue or Secretary tissue.
· Permanent or non-dividing tissue is a group of cells that carry out specific functions but do not divide.
· Meristemetic tissue: Term by C. Negali
· Found in localized plants part with continuous mitotic activities.
· Prominent nuclei, rich in cytoplasm and vacuoles are absent.
· A collection of the small living, thin-walled, isodiametric cells without intercellular spaces and reserve food material like fats, proteins, sugars are present in meristematic tissue.
· Metabolically these are the most active cells. eg. Root meristem, meristem at the apex of the stem, and vascular cambium.
1. Meristematic tissue
2. Permanent tissue
3. Special tissue or Secretary tissue.
1. Meristematic Tissue
· Meristematic tissue or dividing tissue is a group of undifferentiated cells and they can form all kinds of permanent tissues.· Permanent or non-dividing tissue is a group of cells that carry out specific functions but do not divide.
· Meristemetic tissue: Term by C. Negali
· Found in localized plants part with continuous mitotic activities.
· Prominent nuclei, rich in cytoplasm and vacuoles are absent.
· A collection of the small living, thin-walled, isodiametric cells without intercellular spaces and reserve food material like fats, proteins, sugars are present in meristematic tissue.
· Metabolically these are the most active cells. eg. Root meristem, meristem at the apex of the stem, and vascular cambium.
 |
| Fig: Showing Typical Meristematic Tissue. |
· Note: They have cellulosic primary cell walls.
· ER is small in dividing cells.
· Merstematic cells contain more of Salts
· Cells have a conspicuous nucleus and dense cytoplasm.
· Plastids are represented by proplastids.
· The process of change of meristematic tissue into permanent tissue is called differentiation and the reverse process is called de-differentiation. Eg; of de-differentiation is cambium (Vascular, cork, interfascicular) except intrafascicular cambium.
· ER is small in dividing cells.
· Merstematic cells contain more of Salts
· Cells have a conspicuous nucleus and dense cytoplasm.
· Plastids are represented by proplastids.
· The process of change of meristematic tissue into permanent tissue is called differentiation and the reverse process is called de-differentiation. Eg; of de-differentiation is cambium (Vascular, cork, interfascicular) except intrafascicular cambium.
a. Classification of Meristem
i. Based on origin:
A) PROMERISTEM: present in the earliest stage of growing organ and divide to give primary meristem.
B) PRIMARY MERISTEM
· The meristematic cell originates from the embryonic stage of plants or of an organ of plant or pro-meristem.
· These cells are always in an active state of cell division and give rise to primary permanent tissue in the plant body. eg. Apical meristem, intercalary meristem etc.
C) SECONDARY MERISTEM
· It is the meristem that develops from primary permanent tissue at a later stage of life and gives rise to permanent tissue. eg. cork cambium or phellogen develops from the pericycle.
ii. Based on position:
A. PROTODERM – it is the outermost layer that develops forms epidermis
B. PROCAMBIUM – forms vascular tissue.
C. GROUND MERISTEM – forms ground tissue.
· Ground tissue includes hypodermis, cortex, endoderm, pericycle, medullary rays, and pith.
iii. Based upon their location in the plant body
A. APICAL Meristem
· Occur at the shoot and the root tip and responsible for the increase in length.
· They are responsible for the increase in the length of the plant. E.g. all cambium except intra-fascicular cambium
· Differentiated into primary tissues. It is often called subterminal meristem.
Note: It is apical in stem and subterminal in roots.
· Leaf primordia grow into leaf by the activity of apical meristem.
· Axillary bud and terminal bud are derived by the activity of apical meristem.
· In phanerogams, it is represented by a group of cells while in pteridophytes it is represented by a single cell.
· Grasses don’t have apical meristem. They grow by intercalary meristem.
· Haberlandt divide apical meristem into 3 zones:
a) Protoderm: produce epidermal tissue system.
b) Procambium: produce a vascular tissue system.
c) Ground meristem: produce ground tissue system.
a) Protoderm: produce epidermal tissue system.
b) Procambium: produce a vascular tissue system.
c) Ground meristem: produce ground tissue system.
B. LATERAL Meristem
· They lie laterally on stem and roots.
· Present almost parallel to the long axis of the organs e.g. Cork cambium (Phellogen), Vascular cambium.
· Differentiated into secondary tissues.
· Brings about an increase in the width or girth of the organ.
· They lie laterally on stem and roots.
· Present almost parallel to the long axis of the organs e.g. Cork cambium (Phellogen), Vascular cambium.
· Differentiated into secondary tissues.
· Brings about an increase in the width or girth of the organ.
C. INTERCALARY Meristem
· These meristems lie between the permanent tissue as the remnants of the apical meristems. (derived from apical meristem)
· They are present at the base of the node, base of internodes of stems or at the base of leaf or sheathing leaf of monocot.
· Differentiated into primary tissue
· Brings about an increase in the length of the internodes.
· Allow growth in regions other than tips.
· They are in fact a portion of the apical meristem.
Note: The difference between primary growth due to apical meristem and intercalary meristem is that apical meristem is not consumed in the growth process while intercalary meristem is consume
· These meristems lie between the permanent tissue as the remnants of the apical meristems. (derived from apical meristem)
· They are present at the base of the node, base of internodes of stems or at the base of leaf or sheathing leaf of monocot.
· Differentiated into primary tissue
· Brings about an increase in the length of the internodes.
· Allow growth in regions other than tips.
· They are in fact a portion of the apical meristem.
Note: The difference between primary growth due to apical meristem and intercalary meristem is that apical meristem is not consumed in the growth process while intercalary meristem is consume
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| Fig: Meristematic Tissue-based on its position |
Shoot Apex Organization:
Theories of shoot apex organization:
1. Apical cell theory (Purposed by C. Negali):
· According to this theory a single pyramidal cell is responsible for the entire process of growth by division and redividing.
· This theory is applicable only for some higher algae, bryophytes, pteridophytes and is not applicable for gymnosperm and angiosperm (i.e. seed-bearing plants)
Theories of shoot apex organization:
1. Apical cell theory (Purposed by C. Negali):
· According to this theory a single pyramidal cell is responsible for the entire process of growth by division and redividing.
· This theory is applicable only for some higher algae, bryophytes, pteridophytes and is not applicable for gymnosperm and angiosperm (i.e. seed-bearing plants)
2. Histogen theory: (Purposed by Hanstein) (@H = H)
· 3 groups of initials in shoot apex:
a) Dermatogen (Outermost): Gives rise to the epidermis.
b) Periblem (Middle): Gives rise to cortex including endodermis.
c) Pleorome (Innermost): Gives rise to a vascular bundle including pith.
a) Dermatogen (Outermost): Gives rise to the epidermis.
b) Periblem (Middle): Gives rise to cortex including endodermis.
c) Pleorome (Innermost): Gives rise to a vascular bundle including pith.
3. Tunica corpus theory: (Purposed by Schmidt)
b) Corpus:
· The inner mass of a cell is called corpus and it divides both anticlinal and periclinal and produces the bulk of the adult plant.
· The volume of shoot apex is increased by corpus.
Note: Tunica corpus theory is the most accepted theory.
Note:
Anticlinal division:
- Perpendicular to surface.
- Increase in surface area.
Periclinal division:
- Parallel to the surface.
- Helps in increasing the layer to increase the girth in the plant.
2. Histogen concept: (Purposed by Hanstein)
· 4 groups of initials in the root apex.
a) Dermatogen: gives rise to epiblema or piliferous layer or rhizodermis.
b) Periblem: gives rise to cortex including endodermis.
c) Pleorome: gives rise to vascular tissue including pith.
d) Calyptrogen: Forms root cap in monocot.
Note: In dicot, the root cap is formed by dermatogen or epiblem or protoderm.
· They may be primary (permanent tissues parenchyma, collenchyma, sclerenchyma) or secondary permanent tissue (cork, secondary xylem, secondary phloem).
B) Collenchyma:
2. SCLEREIDS or Stone cells
· Highly lignified cells, thick-walled with a narrow lumen.
· Found in the seed of legume.
· Brachysclereids – stone cells.
· Common in shells of nuts, stones of fruits, the flesh of fruits, the flesh of fruits like pear and guava seed coats, cortex, pith and phloem region.
b. Glandular tissue
· Water secreting gland called hydathode is present in colocasia.
· Digestive glands are found in some insectivorous plant-like Drosera.
· Insectivorous plants grow in nitrogen-deficient soil.
· Glandular tissue helps to secrete special substances.
· External glands are present on the epidermis of stem and leaves, generally in the form of outgrowth. eg. hydathodes.
· Digestive glands found in pitcher plants contain proteolytic enzymes to get nitrogen from bodies of insects.
· Resign glands, mucilage glands, oil glands.
Various Types of Cavities in plants
i. Schizogenous Cavity
a. Epidermis
· Epidermis is the outermost continuous tissue layer which is interrupted by minute pores stomata and lenticels.
· Generally epidermis is single-layered but multilayered epidermis is found in Ficus (Banyan) and Nerium (oleander)
b. Cuticle
· Xylem and Phloem are found in separate bundles alternating with each other in different radii.
E.g. Monocot and dicot roots.
c. Concentric vascular bundle
· Xylem and Phloem are present in concentric circles.
i. AMPHICRIBAL or HADROCENTRIC
· Xylem lies in the centre with phloem surrounding it.
· Secondary growth is due to the activity of cork cambium and vascular cambium.
1. Vascular cambium
1. Intrafascicular cambium
ii. FUSIFORM INITIALS:
4. Early Wood or Spring Wood
· Wood formed during spring or early summer.
· Vessels are with a large cavity that helps to increase the rate of transport.
2. In gymnosperm/pteridophyte, Albuminous or Strasburger cells are found instead of the companion cell.
3. In both dicot and monocot leaf, the vascular bundle is conjoint, collateral, closed type and xylem is mesarch. The xylem is surrounded by a colourless bundle sheath in monocot and by a green coloured bundle sheath in dicot.
4. If all the lenticels of the stem are blocked, the first to die will be Shoot tips because lenticels do not occur in roots so no effect on the root.
5. Bark consists of tissue outside the vascular cambium, i.e. Bark = Periderm + cortex + pericycle + phloem.
6. Removal of bark is called girdling, when the plant is girdled the phloem will be removed and there will be no translocation of food to the region lower to stem so the root will die first.
7. Increasing secondary growth in trees causes an increase in the diameter of heartwood.
8. Sieve cells are nucleated while young and becomes enucleated at maturity while the sieve tube is enucleated since young.
9. Dicot leaf is dorsiventral, hypostomatic and horizontal while monocot leaf is isobilateral, amphistomatic and vertical.
10. In a dicot stem vascular bundles are usually arranged in a ring and have cambium.
11. In the monocot leaf the mesophyll is normally not differentiated into spongy and palisade parenchyma.
12. The best method to determine the age of a tree is to count the number of annual rings.
· According to this theory, there are two positions in the shoot apex:
a) Tunica:
· Generally single-layered and outer region and divides only anticlinal (Right angle to the surface of apex that results in surface growth).
· If tunica is more than one layered, the outermost layer forms the epidermis and the inner layer forms cortex and leaf primordial.
a) Tunica:
· Generally single-layered and outer region and divides only anticlinal (Right angle to the surface of apex that results in surface growth).
· If tunica is more than one layered, the outermost layer forms the epidermis and the inner layer forms cortex and leaf primordial.
b) Corpus:
· The inner mass of a cell is called corpus and it divides both anticlinal and periclinal and produces the bulk of the adult plant.
· The volume of shoot apex is increased by corpus.
Note: Tunica corpus theory is the most accepted theory.
Note:
Anticlinal division:
- Perpendicular to surface.
- Increase in surface area.
Periclinal division:
- Parallel to the surface.
- Helps in increasing the layer to increase the girth in the plant.
Root Apex Organization:
· Having simple organization as compared to the shoot apex.
· Root apex is subapical or subterminal in position because
· There is the presence of rot cap (Calyptrogen) at the apex.
· But shoot apex is terminal.
· Having simple organization as compared to the shoot apex.
· Root apex is subapical or subterminal in position because
· There is the presence of rot cap (Calyptrogen) at the apex.
· But shoot apex is terminal.
Different theories of root apex organization:
1. Apical cell theory: (Purposed by C. Negali)
- single apical cell in the root apex is responsible for the entire process of growth.
- Applicable for pteridophytes and gymnosperms and not to angiosperm.
1. Apical cell theory: (Purposed by C. Negali)
- single apical cell in the root apex is responsible for the entire process of growth.
- Applicable for pteridophytes and gymnosperms and not to angiosperm.
2. Histogen concept: (Purposed by Hanstein)
· 4 groups of initials in the root apex.
a) Dermatogen: gives rise to epiblema or piliferous layer or rhizodermis.
b) Periblem: gives rise to cortex including endodermis.
c) Pleorome: gives rise to vascular tissue including pith.
d) Calyptrogen: Forms root cap in monocot.
Note: In dicot, the root cap is formed by dermatogen or epiblem or protoderm.
3. Quiescent centre concept:
- Given by Clowes in maize.
- A/c to this there is an inactive centre in the root apex which is called the quiescent centre(having low DNA, RNA and protein). These cells are at the Go phase.
- The quiescent centre serves as a reserve for replenishment of damaged cells of the meristem.
- Some auxin synthesis also occurs here.
- Given by Clowes in maize.
- A/c to this there is an inactive centre in the root apex which is called the quiescent centre(having low DNA, RNA and protein). These cells are at the Go phase.
- The quiescent centre serves as a reserve for replenishment of damaged cells of the meristem.
- Some auxin synthesis also occurs here.
2. Permanent Tissue
· Permanent tissue are the derivatives of the meristematic cells and lose the power of division.· They may be primary (permanent tissues parenchyma, collenchyma, sclerenchyma) or secondary permanent tissue (cork, secondary xylem, secondary phloem).
· 3 types of Permanent Tissue are:
1. Simple permanent tissue
· It consists of a homogenous cell.
1. Simple permanent tissue
· It consists of a homogenous cell.
 |
| Fig: Showing Different Types of primary permanent tissue. |
A) Parenchyma:
· Simple and most common permanent tissue.
· Thin wall living isodiametric tissue without intercellular space.
· Helps in the storage of food materials and water storage in succulent xerophytes.
· It is the main storage tissue.
i. ARENCHYMA
· Parenchymatous tissue with air space
· Common in hydrophytes which helps in floating.
· Thin wall living isodiametric tissue without intercellular space.
· Helps in the storage of food materials and water storage in succulent xerophytes.
· It is the main storage tissue.
i. ARENCHYMA
· Parenchymatous tissue with air space
· Common in hydrophytes which helps in floating.
ii. CHLORENCHYMA
· Parenchyma having chloroplast, which helps in photosynthesis.
iii. PALISADE PARENCHYMA
· Elongated chlorenchymatous tissue which is common in dicot leaf.
· Elongated chlorenchymatous tissue which is common in dicot leaf.
B) Collenchyma:
· It is a simple non-lignified living medicinal tissue with or without inter cellular space.
· Thick-walled, elongated, living, mechanical tissue.
· Thickening is due to pectin.
· Found in hypodermal region of herbaceous dicot stem.
· Provides elasticity, flexibility, and support to the plant parts.
· Not found in roots (dicot and monocot) and monocot stem.
· Types: Angular, plate and Tubular collenchyma.
· Thick-walled, elongated, living, mechanical tissue.
· Thickening is due to pectin.
· Found in hypodermal region of herbaceous dicot stem.
· Provides elasticity, flexibility, and support to the plant parts.
· Not found in roots (dicot and monocot) and monocot stem.
· Types: Angular, plate and Tubular collenchyma.
C) Sclerenchyma (Stained with Safranin)
· Thick-walled, lignified dead tissue, which develops either from the procambium or secondary deposition on secondary parenchyma.
· Responsible for the support and mechanical strength of the plant.
· These cells are lined with lignin.
· Thick-walled, lignified dead tissue, which develops either from the procambium or secondary deposition on secondary parenchyma.
· Responsible for the support and mechanical strength of the plant.
· These cells are lined with lignin.
1. FIBERS
· Elongated sclerenchymatous tissue with a pointed end wall.
· Thickening is uniform, they mainly provide mechanical support.
· Common in the hypodermal region of the monocot stem.
· They are also found in xylem and phloem tissues.
· Elongated sclerenchymatous tissue with a pointed end wall.
· Thickening is uniform, they mainly provide mechanical support.
· Common in the hypodermal region of the monocot stem.
· They are also found in xylem and phloem tissues.
2. SCLEREIDS or Stone cells
· Highly lignified cells, thick-walled with a narrow lumen.
· Found in the seed of legume.
· Brachysclereids – stone cells.
· Common in shells of nuts, stones of fruits, the flesh of fruits, the flesh of fruits like pear and guava seed coats, cortex, pith and phloem region.
2. Complex Permanent Tissue
· They are made up of two or more or best than two types of cells with common functions.
· They are made up of two or more or best than two types of cells with common functions.
A. Phloem
· Basically for the translocation of the prepared food materials from leaf to the various parts of the plant for storage and growth.
· Made up of 4 types of cells.
i. SIEVE TUBE CELLS
· Common in angiosperm
· Long tube-like nucleus formed by the end-to-end fusion of cells. Pores called 'Sieve pore' perforate their transverse wall.
· Sieve pores are blocked due to the deposition of callose (carbohydrate)
Note: Callus is the mass of undifferentiated cells.
· Basically for the translocation of the prepared food materials from leaf to the various parts of the plant for storage and growth.
· Made up of 4 types of cells.
i. SIEVE TUBE CELLS
· Common in angiosperm
· Long tube-like nucleus formed by the end-to-end fusion of cells. Pores called 'Sieve pore' perforate their transverse wall.
· Sieve pores are blocked due to the deposition of callose (carbohydrate)
Note: Callus is the mass of undifferentiated cells.
ii. COMPANION CELLS
· Found in angiosperm
· In the case of gymnosperm and pteridophytes, albuminous cells are present in place of companion cells.
· They control the function of sieve tube elements.
iii. PHLOEM PARENCHYMA
· They are usually absent in monocot stem.
iv. BAST or PHLOEM FIBERS
· These are only dead cells of Phloem
· Rough textile fibres are obtained from the blast fibres of some plants like jute, which are useful for making ropes and sacks.
· Made up of living cells except for phloem fibres, which are non-living or dead ones.
· Found in angiosperm
· In the case of gymnosperm and pteridophytes, albuminous cells are present in place of companion cells.
· They control the function of sieve tube elements.
iii. PHLOEM PARENCHYMA
· They are usually absent in monocot stem.
iv. BAST or PHLOEM FIBERS
· These are only dead cells of Phloem
· Rough textile fibres are obtained from the blast fibres of some plants like jute, which are useful for making ropes and sacks.
· Made up of living cells except for phloem fibres, which are non-living or dead ones.
B. Xylem
· Responsible for the conduction of water and absorbing minerals from the root to the top of the plant and leaf.
· Provides a mechanical function to the organ concerned.
· Xylem is also called wood (secondary xylem).
· Made up of 4 kinds of cells.
i. TRACHEIDS
· Elongated tube-like dead cells.
· They are only conducting tissues in pteridophytes and gymnosperms.
· Various types of thickenings:
a. Annular – Ring like
b. Spiral – Spiral
c. Reticulate – Net like
d. Scaleriform – Ladder like
e. Pitted
ii. VESSELS
· Elongated tube-like structure formed by several dead cells placed end to end in a row with transverse wall dissolves.
· Similar to tracheids except for end walls.
· Mature vessels lack end walls.
· Forms main conducting tissue in angiosperm.
· Provides mechanical function.
iii. XYLEM PARENCHYMA or WOOD PARENCHYMA
· Only living cell of xylem.
· Involves in lateral conduction.
· Helps in food storage, transport, and conduction of water and minerals.
iv. XYLEM or WOOD FIBERS
· Closely resemble the sclerenchyma fibres.
· Provides mechanical function.
· Xylem is made up of dead cells except for xylem parenchyma.
· Sometimes xylem vessels are blocked by an outgrowth like structure called Tylose.
· The primary xylem is originated from procambium or apical meristem but the secondary xylem develops from vascular cambium or lateral meristem during secondary growth.
· The conducting cells of the xylem are called tracheal elements.
· Genteals (Gnetum, Ephedra) are the gymnosperm with vessels.
· Responsible for the conduction of water and absorbing minerals from the root to the top of the plant and leaf.
· Provides a mechanical function to the organ concerned.
· Xylem is also called wood (secondary xylem).
· Made up of 4 kinds of cells.
i. TRACHEIDS
· Elongated tube-like dead cells.
· They are only conducting tissues in pteridophytes and gymnosperms.
· Various types of thickenings:
a. Annular – Ring like
b. Spiral – Spiral
c. Reticulate – Net like
d. Scaleriform – Ladder like
e. Pitted
ii. VESSELS
· Elongated tube-like structure formed by several dead cells placed end to end in a row with transverse wall dissolves.
· Similar to tracheids except for end walls.
· Mature vessels lack end walls.
· Forms main conducting tissue in angiosperm.
· Provides mechanical function.
iii. XYLEM PARENCHYMA or WOOD PARENCHYMA
· Only living cell of xylem.
· Involves in lateral conduction.
· Helps in food storage, transport, and conduction of water and minerals.
iv. XYLEM or WOOD FIBERS
· Closely resemble the sclerenchyma fibres.
· Provides mechanical function.
· Xylem is made up of dead cells except for xylem parenchyma.
· Sometimes xylem vessels are blocked by an outgrowth like structure called Tylose.
· The primary xylem is originated from procambium or apical meristem but the secondary xylem develops from vascular cambium or lateral meristem during secondary growth.
· The conducting cells of the xylem are called tracheal elements.
· Genteals (Gnetum, Ephedra) are the gymnosperm with vessels.
Based on Origin, Xylem is of two types:
i. PROTOXYLEM
· First formed xylem, which is located in the root and shoot apices.
· Thickening is the annular and spiral type and it is made up of smaller tracheids and vessels.
ii. METAXYLEM
· Later formed xylem which is formed from larger tracheids and vessels.
· Thickening is scalariform or Reticulate or pitted.
· Centrifugal in distribution.
i. PROTOXYLEM
· First formed xylem, which is located in the root and shoot apices.
· Thickening is the annular and spiral type and it is made up of smaller tracheids and vessels.
ii. METAXYLEM
· Later formed xylem which is formed from larger tracheids and vessels.
· Thickening is scalariform or Reticulate or pitted.
· Centrifugal in distribution.
Based on the Position of the Protoxylem:
i. EXARCH
i. EXARCH
· Protoxylem lies towards the outside of the metaxylem.
E.g. Roots (monocot and dicot)
ii. ENDARCH
E.g. Roots (monocot and dicot)
ii. ENDARCH
· Protoxylem elements lie to the centre (centripetal) and the metaxylem develops outward (centrifugally).
Eg. monocot and dicot stem.
iii. MESARCH
iii. MESARCH
Protoxylem lies in between two metaxylem
E.g. Ferns
 |
| Fig: Comparision xylem vs phloem |
3. Special Tissue
· These tissues are usually associated with secretary function.
a. Laticiferous tissue
a. Laticiferous tissue
· Latex secreting tissue
· Latex of Hevea, Maninot, Ficus, and castella is useful for rubber production.
· Latex of papaya contains enzyme papain (helps in protein digestion)
· Latex of papaver (poppy) is the source of Morphine.
· Latex of banana contains Tannin.
· Latififerous tissue consists of latex cells and latex vessels.
· Latex of Hevea, Maninot, Ficus, and castella is useful for rubber production.
· Latex of papaya contains enzyme papain (helps in protein digestion)
· Latex of papaver (poppy) is the source of Morphine.
· Latex of banana contains Tannin.
· Latififerous tissue consists of latex cells and latex vessels.
b. Glandular tissue
· Water secreting gland called hydathode is present in colocasia.
· Digestive glands are found in some insectivorous plant-like Drosera.
· Insectivorous plants grow in nitrogen-deficient soil.
· Glandular tissue helps to secrete special substances.
· External glands are present on the epidermis of stem and leaves, generally in the form of outgrowth. eg. hydathodes.
· Digestive glands found in pitcher plants contain proteolytic enzymes to get nitrogen from bodies of insects.
· Resign glands, mucilage glands, oil glands.
Various Types of Cavities in plants
i. Schizogenous Cavity
· Cavity formed due to the shifting of cells. e.g. Resin canal and mucilage canal.
ii. Lysigenous Cavity
ii. Lysigenous Cavity
· Cavity formed due to breakdown of cells. e.g. oil cavity in citrus.
iii. Schizolysigneous Cavity
iii. Schizolysigneous Cavity
· Protoxylem cavity of monocot stem.
Tissue Structure
i. Epidermal Tissue Systema. Epidermis
· Epidermis is the outermost continuous tissue layer which is interrupted by minute pores stomata and lenticels.
· Generally epidermis is single-layered but multilayered epidermis is found in Ficus (Banyan) and Nerium (oleander)
b. Cuticle
· In xerophytes cuticle is thick, in Mesophytes it is moderately thick and is absent in hydrophytes.
· It is also absent in roots and underground parts.
c. STOMATA
Stoma contains
1. Subsidiary cells
2. Guard cells
· Guard cells are single in mass capsules and double in monocots and dicots.
· Stomata are kidney or bean-shaped in dicots and they are dumbbell-shaped in monocots.
· Sunken stomata are the characteristics of Xerophytes.
c. STOMATA
Stoma contains
1. Subsidiary cells
2. Guard cells
· Guard cells are single in mass capsules and double in monocots and dicots.
· Stomata are kidney or bean-shaped in dicots and they are dumbbell-shaped in monocots.
· Sunken stomata are the characteristics of Xerophytes.
· Stomata are either absent or inactive (Potamogeton type) in the leaves of submerged plants.
d. Trichome or Hairs
a. Unicellular in – Roots (Dicot and monocot)
b. Multi cellular in – Dicot stem.
d. Trichome or Hairs
a. Unicellular in – Roots (Dicot and monocot)
b. Multi cellular in – Dicot stem.
ii. Ground Tissue System
a. HYPODERMIS
(a) Collenchymatous: Eg. dicot stem.
(b) Sclerenchymatous: Eg. monocot stem
b. GENERAL CORTEX
a. HYPODERMIS
(a) Collenchymatous: Eg. dicot stem.
(b) Sclerenchymatous: Eg. monocot stem
b. GENERAL CORTEX
· indistinct in monocot
· It is present inside the hypodermis and the inner rest layer of it is called the endodermis.
c. ENDODERMIS
· In-root – Suberised endodermal cells are called Casparian stripe.
· Non-suberised endodermal cells are called passage cells.
· In dicot stem-endodermis is called a starch sheath.
d. PERICYCLE
· Lateral roots originate from pericycle which is endogenous in origin.
· In the case of dicot root, it can form vascular cambium.
· Lies just inside endodermis.
e. MEDULLARY RAYS or CONJUNCTIVE TISSUE
· The pore of the plant axis is occupied by a mass of parenchymatous tissue called medulla or pith.
· Medullary rays – in dicot stem
· Conjunctive tissue – in roots
· Meristematic in nature
f. PITH
· Well developed in monocot root and dicot stem.
· Not distinct in monocot stem
· It is present inside the hypodermis and the inner rest layer of it is called the endodermis.
c. ENDODERMIS
· In-root – Suberised endodermal cells are called Casparian stripe.
· Non-suberised endodermal cells are called passage cells.
· In dicot stem-endodermis is called a starch sheath.
d. PERICYCLE
· Lateral roots originate from pericycle which is endogenous in origin.
· In the case of dicot root, it can form vascular cambium.
· Lies just inside endodermis.
e. MEDULLARY RAYS or CONJUNCTIVE TISSUE
· The pore of the plant axis is occupied by a mass of parenchymatous tissue called medulla or pith.
· Medullary rays – in dicot stem
· Conjunctive tissue – in roots
· Meristematic in nature
f. PITH
· Well developed in monocot root and dicot stem.
· Not distinct in monocot stem
Vascular Bundles and Types
a. Radial vascular bundle· Xylem and Phloem are found in separate bundles alternating with each other in different radii.
E.g. Monocot and dicot roots.
b. Conjoint vascular bundle
· Xylem and Phloem are present in the same vascular bundle on the same radius.
· Xylem and Phloem are present in the same vascular bundle on the same radius.
i. COLLATERAL
· Xylem is placed towards inside and phloem towards outside.
a. Collateral open
· Xylem is placed towards inside and phloem towards outside.
a. Collateral open
· cambium is present in between xylem and phloem.
E.g., Dicot stems
b. Collateral closed
b. Collateral closed
· cambium is absent between xylem and phloem
E.g. Monocot stems (MC3)
ii. BICOLLATERAL
· Cambium and phloem occurs twice
· Arrangement of vascular tissue is phloem - cambium – xylem – cambium – Phloem
E.g., Dicot stems of the gourd family Cucurbita, cucumbers (Cucurbitaceae family)
ii. BICOLLATERAL
· Cambium and phloem occurs twice
· Arrangement of vascular tissue is phloem - cambium – xylem – cambium – Phloem
E.g., Dicot stems of the gourd family Cucurbita, cucumbers (Cucurbitaceae family)
c. Concentric vascular bundle
· Xylem and Phloem are present in concentric circles.
i. AMPHICRIBAL or HADROCENTRIC
· Xylem lies in the centre with phloem surrounding it.
E.g. Fern plants
ii. AMPHIVASAL or LEPTOCENTRIC
· Phloem lies in the centre with Xylem surrounding it.
ii. AMPHIVASAL or LEPTOCENTRIC
· Phloem lies in the centre with Xylem surrounding it.
E.g. Yucca and Dracenea
· Stoma and cuticle are absent.
· Casparian strips are prominent in dicot roots.
· In dicot roots, xylem bundles are diarch to hexarch (i.e. 2 – 6)
· Xylem and phloem bundles are polyarch i.e. > 8 in monocot root.
· No. of Vascular bundles in dicot root is 2-6 (Diarch to hexarch)
· No. of vascular bundles in monocot root is more than six (Polyarch)
· Secondary growth takes place in dicot.
· Scattered vascular bundles are found in monocot stem, which is variable in size.
· Water cavity is found in monocot stem.
· Cambium is well developed in dicot stem but absent in monocot stem.
· Grafting is not possible in monocot because they lack cambium.
Root
· Roots have the outermost epiblem a which bears a large number of short-lived unicellular root hairs arising from piliferous cells.· Stoma and cuticle are absent.
· Casparian strips are prominent in dicot roots.
· In dicot roots, xylem bundles are diarch to hexarch (i.e. 2 – 6)
· Xylem and phloem bundles are polyarch i.e. > 8 in monocot root.
· No. of Vascular bundles in dicot root is 2-6 (Diarch to hexarch)
· No. of vascular bundles in monocot root is more than six (Polyarch)
· Secondary growth takes place in dicot.
Stem
· Vascular bundles are arranged in rings in the dicot stem.· Scattered vascular bundles are found in monocot stem, which is variable in size.
· Water cavity is found in monocot stem.
· Cambium is well developed in dicot stem but absent in monocot stem.
· Grafting is not possible in monocot because they lack cambium.
Leaf
| Dicot | Monocot |
|---|---|
| Dorsiventral. | Isobilateral. |
| The mesophyll is differentiated into palisade and spongy mesophyll. | No differentiation of mesophyll |
| More stomata towards the lower surface than the upper surface. | Equal distribution of stomata on both sides of the leaf. |
| Bulliform cells are absent. | Presence of bulliform cells. |
· Bulliform cells or motor cells are found in the monocot leaves, which helps in rolling of leaves.
· Cambium is absent in leaves.
· Cambium is absent in leaves.
Secondary Growth
· Increase in thickness or girth due to the activity of cambium and cork cambium.· Secondary growth is due to the activity of cork cambium and vascular cambium.
1. Vascular cambium
1. Intrafascicular cambium
Eg. cambium within the single bundle.
2. Interfascicular cambium
2. Interfascicular cambium
· cambium between two vascular bundles
E.g. between xylem and phloem.
· Secondary growth occurs only in dicots or dicot stem.
· Vascular bundles in dicot stem – conjoint, collateral and open type.
· Interfascicular and intrafascicular cambium forms cambium ring.
· Secondary growth occurs only in dicots or dicot stem.
· Vascular bundles in dicot stem – conjoint, collateral and open type.
· Interfascicular and intrafascicular cambium forms cambium ring.
The vascular cambium has two types of cells:
i. RAY INITIALS:
i. RAY INITIALS:
· Spherical or isodiametric is shape.
· They divide to form parenchymatous cells, which forms secondary medullary rays, in between neighbouring xylem and phloem.
ii. FUSIFORM INITIALS:
· Narrow and elongated cells.
· They divide to form an inner cell and an outer cell.
· It forms the secondary xylem towards the centre and the secondary phloem towards the periphery.
· Cambium is more active on the inner side than outside.
· Secondary xylem occupies the major portion of the stem forming a hard compact mass.
· Cambium is more active on the inner side than outside.
· Secondary xylem occupies the major portion of the stem forming a hard compact mass.
2. Cork Cambium
· Originate in the cortex
· Which is also called Phellogen, which forms phellem (cork) towards the periphery and phelloderm (secondary cortex) towards the inner side.
· Phellogen, Phellem and Phelloderm form periderm.
· Cork is commercially obtained from Quercus suber (oak tree, a temperate plant)
· All new tissue, cork cambium secondary cortex and cork formed in the peripheral region are together known as periderm and all the dead cells lying outside cambium is called bark.
· Originate in the cortex
· Which is also called Phellogen, which forms phellem (cork) towards the periphery and phelloderm (secondary cortex) towards the inner side.
· Phellogen, Phellem and Phelloderm form periderm.
· Cork is commercially obtained from Quercus suber (oak tree, a temperate plant)
· All new tissue, cork cambium secondary cortex and cork formed in the peripheral region are together known as periderm and all the dead cells lying outside cambium is called bark.
3. Annual Ring
· It is a ring of Secondary xylem formed in a year.
· Secondary xylem is formed twice a year. i.e. two concentric rings of spring and autumn wood.
· It is a ring of Secondary xylem formed in a year.
· Secondary xylem is formed twice a year. i.e. two concentric rings of spring and autumn wood.
4. Early Wood or Spring Wood
· Wood formed during spring or early summer.
· Vessels are with a large cavity that helps to increase the rate of transport.
5. Late Wood or Autumn Wood
· Wood formed during autumn or winter
· Vessels are fewer in numbers with narrow cavities.
· Annual ring is formed by one ring of springwood and one ring of autumn wood. It corresponds to a growth period of one year.
· Year after year, these rings are formed and hence the growth of a tree can be calculated by counting these annual rings, which is known as Dendrochronology.
· Annual rings are distinct in cold climatic conditions or temperate plants.
· Annual rings are indistinct in Tropical plants.
· Plant growing near to seashore shows indistinct annual rings.
· Porous wood: Wood made up of vessels. e.g. Angiosperms.
· Non-Porous wood: Wood lacks vessels and is made up of tracheids. e.g. Gymnosperms.
· Wood formed during autumn or winter
· Vessels are fewer in numbers with narrow cavities.
· Annual ring is formed by one ring of springwood and one ring of autumn wood. It corresponds to a growth period of one year.
· Year after year, these rings are formed and hence the growth of a tree can be calculated by counting these annual rings, which is known as Dendrochronology.
· Annual rings are distinct in cold climatic conditions or temperate plants.
· Annual rings are indistinct in Tropical plants.
· Plant growing near to seashore shows indistinct annual rings.
· Porous wood: Wood made up of vessels. e.g. Angiosperms.
· Non-Porous wood: Wood lacks vessels and is made up of tracheids. e.g. Gymnosperms.
6. Sapwood
· Forms outer region or peripheral region of stem.
· Living wood.
· Conduct water and minerals
· Often called Alburnum
· Susceptible to damage by microorganisms.
· Forms outer region or peripheral region of stem.
· Living wood.
· Conduct water and minerals
· Often called Alburnum
· Susceptible to damage by microorganisms.
7. Heart Wood
· Wood is present at the centre of the stem.
· Often called Duramen or dead wood.
· Does not conduct water and minerals.
· Hard, more resistant, durable etc.
· It is blocked with dark staining deposits like tannins, oils, aromatics substances, gums, resins etc.
Hard Wood: Wood of angiosperms, which contain vessels.
Soft Wood: Wood of gymnosperms (the conifers) that does not contain vessels.
· Wood is present at the centre of the stem.
· Often called Duramen or dead wood.
· Does not conduct water and minerals.
· Hard, more resistant, durable etc.
· It is blocked with dark staining deposits like tannins, oils, aromatics substances, gums, resins etc.
Hard Wood: Wood of angiosperms, which contain vessels.
Soft Wood: Wood of gymnosperms (the conifers) that does not contain vessels.
8. Cork and Bark
· Cork cells are filled with suberin and are impermeable to water and gases.
· The cork has small openings, which are visible as scars on its surface. These are called lenticels.
· Cork cells are filled with suberin and are impermeable to water and gases.
· The cork has small openings, which are visible as scars on its surface. These are called lenticels.
9. Scale Bark
· Bark is removed in the form of small patches. E.g. Guava
· Bark is removed in the form of small patches. E.g. Guava
Notes:
Tyloses
Tyloses
· Balloon like an outgrowth of ray parenchyma inside the cavity of vessels. It results in the blockage of vessels.
· Lateral roots originate from pericycle and are endogenous in nature.
· Root hairs and stem branches are exogenous in nature.
· Lateral roots originate from pericycle and are endogenous in nature.
· Root hairs and stem branches are exogenous in nature.
Natural Bark
· Made up of all the tissues lying outside the cork cambium.
· Non–technically bark is defined as the region lying outside the vascular cambium (carpenter's bark).
· When the bark is removed by ringing, roots die first then shoot dies.
· Ringing ultimately kills the whole plant.
· Made up of all the tissues lying outside the cork cambium.
· Non–technically bark is defined as the region lying outside the vascular cambium (carpenter's bark).
· When the bark is removed by ringing, roots die first then shoot dies.
· Ringing ultimately kills the whole plant.
Ring Bark
· Bark is removed in the form of a sheet.
E.g. Betula (Birch or Bhojpatra)
· Betula forms temperate forest.
· Bark is removed in the form of a sheet.
E.g. Betula (Birch or Bhojpatra)
· Betula forms temperate forest.
High Yielding Points from Plant Anatomy
1. Apical cell theory is given by Nageli, Histogen theory is given by Hainstain, Quiescent centre theory is given by Clows.2. In gymnosperm/pteridophyte, Albuminous or Strasburger cells are found instead of the companion cell.
3. In both dicot and monocot leaf, the vascular bundle is conjoint, collateral, closed type and xylem is mesarch. The xylem is surrounded by a colourless bundle sheath in monocot and by a green coloured bundle sheath in dicot.
4. If all the lenticels of the stem are blocked, the first to die will be Shoot tips because lenticels do not occur in roots so no effect on the root.
5. Bark consists of tissue outside the vascular cambium, i.e. Bark = Periderm + cortex + pericycle + phloem.
6. Removal of bark is called girdling, when the plant is girdled the phloem will be removed and there will be no translocation of food to the region lower to stem so the root will die first.
7. Increasing secondary growth in trees causes an increase in the diameter of heartwood.
8. Sieve cells are nucleated while young and becomes enucleated at maturity while the sieve tube is enucleated since young.
9. Dicot leaf is dorsiventral, hypostomatic and horizontal while monocot leaf is isobilateral, amphistomatic and vertical.
10. In a dicot stem vascular bundles are usually arranged in a ring and have cambium.
11. In the monocot leaf the mesophyll is normally not differentiated into spongy and palisade parenchyma.
12. The best method to determine the age of a tree is to count the number of annual rings.
Also, Read Notes of Other Lessons of Botany: