AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants


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AP Inter 1st Year Botany Notes 12th Lesson Histology and Anatomy of Flowering Plants

→ Anatomically, the plant body is made up of different types of tissues.

→ The plant tissues are two types namely Meriste- matic and permanent.

→ A group of Immature cells which are in a state of Division are called meristematic tissues.

→ They may be apical or Inter calary or Lateral, based on the pisition.

→ A group of mature cells, which lost the power of division and acquire definite shape are called permanent tissues.

→ They are of three types namely, Simple, Complex and Special tissues.

→ A group of similar cells which perform same function are called simple tissues. They are Parenchyma, Collenchyma and Sclerenchyma.

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ A group of more than one type of cells and work together are called Complex tissues. They xylem and phloem.

→ Based on the structure and location, tissue systems are classified into three types. They are Epidermal tissue system, Ground Tissue system and vascular Tissue system.

→ Epidermial tissue system includes Epidermis, the stomata, Cuticle and Hairs.

→ The Ground Tissue system includes, tissues except Epidermis and vascular Bundles.

→ The Vascular Tissue System includes Xylem and phloem.

→ Vascular bundles may be collateral open (Dicot stem) collateral closed (Monocot stem) Radial (Roots) or Bicollateral (Cucurbita) type.

→ The Internal structure of Dicotylednous root shows Epidermis, cortex and stele. The stele shows xylem and phloem arranged radially and usually Tetrarch.

→ In the Internal structure of Monocotyledonous root, the stele shows xylem and phloem, arranged radially with Polyarch xylem.

→ In Dicot stem. Internally 15-20 Vascular bundles are present, arranged in one ring, called Eustele.

→ In Monocot stem, several vascular Bundles are present, Scattered irregularly in the ground tissue called attactostele.

→ In Dicot leaf. Internally Mesophyll is differentiated into palisada and spongy parenchyma where as in Monocot leaf, Mesophyll contains only spongy parenchyma.

→ Dicotyledonous stems and Roots Increase in Girth due to vascular cambium and Cork cambium is called secondary growth.

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ Intrafascicular cambium and Interfascicular cambium joined together to form cambial ring.

→ Spring wood and Autumn wood together called annual Ring. By counting the number of annual rings, the approximate age of trees can be estimated. This Branch of science is called Dendrochronology.

→ In older trees, the central part of the wood is dark brown and is highly durable called Heart wood or Duramen.

→ The peripheral part of the wood is light in colour and is known as sap wood.

→ The cortical cells become meristematic and form cork cambium or phellogen.

→ Phellogen, Phellem (Outer Cork), Phelloderm (Inner Secondary Cortex) together called periderm.

→ In old stem, lens shaped openings are formed called Lenticels, help in exchange of gases.

→ Annual ring : The spring wood and autumn wood that appear in a year as concentric ring in secondary organs of dicotyledons constitute annual ring. By counting the number of annual rings, the approximate age of trees can be estimated,

→ Autumn or late wood : The wood having vessels with narrow lumens is called autumn wood. It is formed in autumn season.

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ Bicollateral vascular bundle : Phloem is present on either side of the xylem separated by cambia.

→ Bulliform cells : These are the large, empty and colourless cells present in adaxial epidermis of isobilateral leaves. They help in rolling and unrolling of the leaves.

→ Casparian strips : These are water impermeable, waxy suberised bands deposited on tangential as well as radial walls of the endodermal cells.

→ Complex tissues : Permanent tissues having many different types of cells are called complex tissues.

→ Conjoint vascular bundle : This is one type of vascular bundle In which the xylem and phloem are present at the same radius of vascular bundle.

→ Endarch : The protoxylem lies towards the centre (pith) and the metaxylem towards the periphery of the organ. This type of arrangement of xylem Is found in stems.

→ Exarch : The protoxylem lies towards periphery and metaxylem lies towards the centre. This type of arrangement of primary xylem is found in roots.

→ Fibres : These are thick walled elongated and pointed cells of sclerenchyma generally occurring in groups.

→ Heart wood : The dark brown coloured central part of secondary xylem comprising of dead elements with highly lignified walls is called heart wood. It Is infiltrated with various organic compounds like tannins, resins, oils, gums, aromatic substances and essential oils. The heart wood does not conduct water but it gives mechanical support to the stem.

→ Lenticels : Lens shaped openings in the cork of woody trees are called lenticels. They show closely arranged parenchymatous cells. The lenticels permit the exchange of gases between the outer atmosphere and the internal tissues of the woody organs.

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ Meristems : These are specialised regions of active cell division in plants.

→ Periderm: Phellogen, Phellem and phelloderm are collectively known as periderm.

→ Phellem: Cork tissue formed from the cells cut off from the phellogen.

→ Phelloderm : Cells formed on inner side of cork cambium constituting secondary cortex.

→ Phellogen: It Is also called cork cambium which appears usually in cortex. This produces phellem and phelloderm.

→ Sap wood : The peripheral region of the secondary xylem Is lighter in colour and is known as the sap wood. It conducts water and minerals from root to leaf.

→ Sclereids : These are spherical, oval or cylindrical, highly thickened sclerenchymatous dead cells with very narrow lumens.

→ Simple tissues : Permanent tissues having all cells similar in structure and function are called simple tissues.

→ Spring or early wood : The wood having vessels with wide lumens is known as spring wood. It is formed in spring season.

→ Starch sheath : The endodermis is called starch sheath as the cells are rich with starch grains.

→ Stomatal apparatus : The stomatal aperture, guard cells and the surrounding subsidiary cells are together called stomatal apparatus.

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ Histology is the study of different tissues in the plant body.

→ Anatomy is the study of internal structure and arrangement of various tissues.

→ Anatomically a plant is made up of different kinds of tissues.

→ Plant tissues are classified into (i) Meristematic tissues (ii) Permanent tissues.

→ Meristematic tissue comprises meristematic cells which help in the growth of the plant body.

→ Based on the location Meristematic tissues are (i) Apical (ii) Intercalary (iii) Lateral [IPE]

→ Xylem and Phloem are the complex tissues.

→ Xylem is meant for the conduction of water and phloem is for the conduction of food materials.

→ There are three types of tissue systems – Epidermal, Ground and Vascular.

→ The epidermal tissue systems are made of epidermal cells, stomata and the epidermal appendages.

→ Stomata are present on leaves and young stems. [IPE]

→ Lenticels are pores present on old stems and old aerial roots. [IPE]

→ The ground tissue system forms the main bulk of the plant.

→ It is divided into three zones – cortex, pericycle and pith.

→ The vascular tissue system is formed by the xylem and phloem.

→ Monocot and dicot plants show marked variation in their internal structures.

→ But the anatomy of monocot root and dicot root is more or less similar.

→ Periderm: The corkey outer layer of a plant system formed as a secondary covering in response to injury or infection is called Periderm. [IPE]

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ Epidermis is with unicellular root hairs, cuticle. Stomata are absent.

→ Exodermis is with suberised cells. General cortex is parenchymatous.

→ Endodermis shows casparian thickenings. Pericycle is parenchymatous.

→ Pith or Medulla is scanty or absent in dicot root and well developed in monocot root.

→ Vascular bundles are conjoint, collateral, open in dicots and closed in monocots stem.

→ T.S of dicot stem: (i) Epidermis (ii) Cortex (iii) Stele [IPE]

  1. Epidermis: Epidermis is outer most layer.
  2. Cortex: The part between epidermis and stele is called cortex.
    It is composed of (a) Hypodermis (b) General cortex (c) Endodermis
  3. Stele: Stele is the central conducting cylinder.
    It is composed of (a) pericycle (b) vascular bundles (c) medulla (d) Medullary rays.

→ T.S of Monocot Stem: (i) Epidermis (ii) Hypodermis (iii) Ground tissue (iv) Vascular bundles

→ T.S of dicot root: (i) Epidermis (ii) Cortex (iii) Stele (IPE]

→ T.S of Monocot root: (i) Epidermis (ii) Cortex (iii) Stele [IPE]

→ The reason for curling of grass leaves inwards during very dry weather is due to flacidity of bulliform cells. [NEET 2019]

→ Phloem in gymnosperms lack both seive tubes and companion cells. [NEET 2019]

→ Xylem translocates water, mineral salts some organic nitrogen only. [NEET 2019]

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ The morphological nature of the edible part of coconut is endosperm. [NEET-2017]

→ In Bougainvillea, thorns are the modifications of stem. [NEET-2017]

→ Coconut fruit is a drupe. [NEET-2017]

→ Cortex is the region found between epidermis and stele. [NEET-2016]

→ Free-central placentation is found in Dianthus. [NEET-2016]

→ Radial symmetry is found in the flowers of Brassica. [NEET-2016]

→ The term ‘polyadelphous’ is related to androecium. [NEET-2016]

→ Specialised epidermal cells surrounding the guard cells are called subsidiary cells. [NEET-2016]

→ The standard petal of a papilionaceous corolla is also called vexillum. [NEET-2016]

→ Cotyledon of maize grain is called scutellum. [NEET-2016]

→ Stems modified into flat green organs performing the functions of leaves are known as phylloclades. [NEET-2016]

→ Roots play insignificant role in absorption of water in Pistia. [NEET-2015]

→ Vascular bundles in monocotyledons are considered closed because cambium is absent. [NEET-2015]

→ A major characteristic of monocot root is the presence of vasculature without cambium. [NEET-2015]

→ Leaves become modified into spines in Opuntia. [NEET-2015]

→ Keel is the characteristic feature of flower of Indigofera. [NEET-2015]

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ Perigynous flowers are found in rose. [NEET-2015]

→ An aggregate fruit is one which develops from multicarpellary apocarpous gyhoecium [NEET-2014]

→ An example of edible underground stem is potato. [NEET-2014]

→ Trachieds differ from other tracheary elements in being imperforate. [NEET-2014]

→ Placenta and pericarp are both edible portioins in tomato. [NEET-2014]

→ Age of a tree can be estimated by number of annual rings. [NEET-2013]

→ Lenticels are involved in gaseous exchange. [NEET-2013]

→ Perisperm differs from endosperm in being a diploid tissue. [NEET-2013]

→ As compared to a dicot root, a monocot root has many xylem bundles. [2012 PMT]

→ Vexillary aestivation is characteristic of the family Fabaceae. [2012 PMT]

→ The coconut water and the edible part of coconut are equivalent to endosperm. [2012 PMT]

→ Water containing cavities in vascular bundles are found in maize. [2012 PMT]

AP Inter 1st Year Botany Notes Chapter 12 Histology and Anatomy of Flowering Plants

→ Closed vascular bundles lack cambium. [2012 PMT]

→ The gynoecium consists of many free pistils in flowers of Michelia. [2012 PMT]

→ Phyllode is present in Australian Acacia. [2012 PMT]

→ Cymose inflorescence is present in Solanum [2012 PMT]

→ Placentation in tomato and lemon is axile. [2012 PMT]

→ Companion cells are closely associated with sieve elements. [2012 PMT]

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