Anatomy of Flowering Plants: Class 11 Biology NCERT Chapter 6

Key Features of NCERT Material for Class 11 Biology Chapter 6 – Anatomy of Flowering Plants

In the previous chapter: Morphology of Flowering Plant, you will learn about how Morphology is the name given to the science that deals with the study of the form and structure of things. In chapter 6 of NCERT class 11 Biology book: Anatomy of Flowering Plants, we will learn about Anatomy and how it concerned with the study of internal structures or an organ system of an organism. 

An assortment of cells playing out a particular capacity is called tissue. Plant tissues can be assembled into plant tissue frameworks each performing specific capacities. A plant tissue framework is characterized as a useful unit, associating all organs of a plant. Plant tissue framework is likewise assembled into different tissues depending on their capacities. How about we discover more.

Types of Plant Tissues

Types of Plant Tissues

Quick revision notes

Life systems are the study of the inner structure of living being. Study of plant life systems incorporates histology-investigation of association and structure of tissues. Life systems help in knowing the basic quirks of the various gathering of plants and demonstrates the auxiliary variation to differing situations. 

The tissue 

Anatomy of Flowering Plants: plants tissue

A gathering of cells having a typical root and as a rule, performing normal capacity are called tissues.

  • Meristematic tissue is a basic tissue made out of a gathering of comparable and juvenile cells which can partition and structure new cells. The meristem which happens at tips of roots and shoots are called apical meristem.
  • Intercalary meristem happens between developing tissues, particularly in grasses. Both apical meristems and intercalary meristems are essential meristems since they show up from the get-go in the life of a plant and help to shape the essential plant body.
  • The meristem which happens on the sides and partakes in expanding the size of the plants are called Lateral meristem. Intrafascicular cambium in the essential parallel meristem. Vascular cambium, stopper cambium are optional meristem.
  • The phones that have become fundamentally and practically particular and lose the capacity to partition are called changeless tissue. Perpetual tissues having all phones comparable in structure and capacity are called simple permanent tissues and those having various types of cells are called complex tissue. 
  • Parenchyma is a straightforward changeless living tissue which is comprised of meagre walled isodiametric cells. Every cell encases a huge focal vacuole and fringe cytoplasm containing core. They are found in non-woody and delicate territories of stem, root, leaves, leafy foods. They store the food and give bloat to milder pieces of plant.

Intercelluar space: Anatomy of Flowering Plants

  • Collenchyma comprises of cells which are highly thickened at corner because of cellulose, hemicellulose and gelatin. Oval, round or polygonal regularly contains chlorophyll. They offer mechanical help to the developing pieces of plants like youthful stem.

Anatomy of Flowering Plants

  • Sclerenchymas are steady tissue having profoundly thick-walled cells with practically no cellular material because of the statement of cellulose or lignin. They are of two sorts: strands and sclereids. They offer mechanical help to develop plant organs to endure twisting, shearing, pressure and so on.

Sclerenchymas: Anatomy of Flowering Plants

Complex Tissues

Xylem and phloem establish the mind-boggling tissues in plants and work all together.

Xylem Phloem
  1. It conducts water or sap.
  2. Xylem is found deep in the plant.
  3. Xylem provides mechanical strength.
  4. It is made up of tracheid, vessels, xylem fibre and xylem parenchyma.
  1. Phloem conducts organic food.
  2. It is situated towards the outer side.
  3. It has no mechanical functions.
  4. It is made up of sieve tube, phloem, companion cells, parenchyma and phloem fibres.
  • Essential xylem is of two kinds protoxylem and metaxylem. In stem, protoxylem lies in focus and metaxylem towards outskirts. This sort of essential xylem is called endarch. 
  • In roots, protoxylem lies in outskirts and metaxylem lies towards the middle. This sort of essential xylem is called an exarch. 
  • In gymnosperms, albuminous cells and strainer cells need sieve tube and partner cells.

Epidermal Tissue System

  • It frames the furthest covering of entire plant body, which comprises of epidermal cells, stomata, epidermal extremities (trichomes and hairs). 
  • The epidermis is single-layered, parenchymatous with waxy thick layers of fingernail skin to forestall water misfortune. 
  • Stomata is available in the epidermis of leaves. It controls the happening and vaporous trade. In dicots, stomata are bean-moulded having two gatekeeper cells shutting the stomatal pore. In monocots, the stoma is free weight moulded. Watchman cells contain chloroplasts and help in opening and shutting of stomata. 
  • Gatekeeper cells are encircled by auxiliary cells. The stomatal gap, monitor 
  • cells and the encompassing auxiliary cells are together called the stomatal mechanical assembly

Dicots (Bean shaped) Monocots (Dumb-bell shaped)

Dicots (Bean shaped) Monocots (Dumb-bell shaped)

Epidermis additionally contains various hairs. Root hairs are unicellular prolongation of epidermal cells. Trichomes are available on stems, which are multicellular, expanded or un-stretched forestalling water misfortune because of happening.

The ground Tissue System

  • All the tissue among epidermis and vascular pack shape the ground tissues. It comprises of straightforward lasting tissues. Parenchyma is available in pericycle, cortex, essence and medullary beams in stem and roots. 
  • In leaves, the mesophyll, chloroplast containing cell, shapes the ground tissues

The Vascular Tissue System

The Vascular Tissue System

  • The vascular framework comprises of complex tissues, xylem and phloem that together structure vascular groups.
  • At the point when xylem and phloem inside a vascular group are masterminded in substitute way on various radii, the course of action is called spiral as in roots. At the point when xylem and phloem are arranged at a similar span of the vascular pack, it is called conjoint as in stem and leaves.

xylem and phloem: Anatomy of Flowering Plants

Radial

Dicotyledonous Root 

  • The peripheral layer of the dicot root is epidermis containing unicellular root hairs. 
  • The cortex comprises of a few layers of flimsy walled parenchyma cells. 
  • The deepest layer of the cortex is called endodermis having waxy material suberin as Casparian strips, which is impermeable to water. 

Monocotyledonous Root 

  • The life structures of the monocot root are like the dicot root in numerous regards. 
  • It has epidermis, cortex, endodermis, pericycle, vascular packages and substance. As contrasted with the dicot root which has fewer xylem groups 

Dicotyledonous Stem 

  • Epidermis: is secured with a slender layer of fingernail skin and may have Trichomes and stomata. 
  • Cortex: The cortex is comprised of the different layers of cells including hypodermis, a center layer of parenchyma cells and a deepest layer called endodermis.
  • Endodermis cells are prosperous in starch grains and are known as the starch sheath. The pericycle is available on the internal side of endodermis. Layers of radially positioned parenchyma between the vascular groups are called medullary beams. 
  • Countless vascular groups are organized in a ring. Each vascular pack is conjoint, open. Protoxylem is endarch

Monocotyledonous Stem

  • The hypodermis is comprised of sclerenchyma. Vascular packs are conjoint, shut and dissipated. Each vascular group is encircled by a sclerenchymatous pack sheath. 
  • Phloem parenchyma is missing. Water-containing pits are available inside the vascular groups.

Dorsiventral (Dicotyledonous) Leaf

  • The leaf lamina of a dorsiventral leaf has 3 sections: epidermis, mesophyll and vascular framework. 
  • The upper epidermis is termed the adaxial epidermis and the lower one is called the abaxial epidermis. More number of stomata are available on the abaxial epidermis. 
  • There are two sorts of cells in the mesophyll: palisade parenchyma and springy parenchyma. The palisade parenchyma is set adaxially. 
  • The springy parenchyma is arranged underneath the palisade parenchyma and reaches out to the lower epidermis. There are various enormous spaces and air cavities between the cells of light parenchyma. 
  • Vascular packs are encircled by a layer of thick-walled group sheath cells.

Isobilateral (Monocotyledonous) Leaf

  • Stomata are available on both the surfaces of an isobilateral leaf. The mesophyll isn’t parted into palisade and springy parenchyma. 
  • Some adaxial epidermal cells in grasses are altered into huge, void cells called bulliform cells. When the bulliform cells assimilate water, they become bloated. So the leaf surface is uncovered. During water pressure, when the bulliform cells become limp, the leaves twist inwards to limit water misfortune.

Secondary GROWTH 

The expansion in the circumference of a plant body is called secondary development. The tissues engaged with secondary development are vascular cambium and stopper cambium. 

Vascular Cambium: 

In the event of youthful stem, vascular cambium is available in patches as a solitary layer between the xylem and phloem. It frames a total ring at a later stage. 

The activity of the Cambial Ring: 

  • The cambial ring gets dynamic and starts to cut off new cells, both towards the internal and the external sides. 
  • The cells which are cut off towards substance develop into auxiliary xylem. The cells which are cut off towards outskirts develop into optional phloem. 
  • The cambium is more dynamic on the internal side than on the external. Subsequently, the measure of optional xylem created is more than auxiliary phloem. The primary and secondary phloems get step by step squashed because of the formation and gathering of secondary xylem. 
  • At certain spots, the cambium shapes a tight band of parenchyma, which goes through the secondary xylem and the secondary phloem in the outspread ways. These are the secondary medullary beams 

Springwood and harvest time wood: 

  • Cambium is extremely dynamic throughout the spring season, yet less dynamic during the winters. Thus, during spring; countless xylem components are shaped having more extensive vessels. During winter, fewer xylem components are shaped having thin vessels. 
  • The wood-framed during summer is called springwood. The wood developed during winter is called autumn wood. 
  • The two sorts of the wood show up as exchange concentric rings in cross over a segment of a trunk of a tree. These are called annual rings and give data about the age of the tree. 

Heartwood and sapwood: 

  • In old trees, most of the secondary xylem is dull in colour, hard and impervious to attacks by microorganisms and bug. This locale is made of dead components with exceptionally lignified. This wood is called heartwood. The heartwood gives mechanical help however doesn’t lead water. 
  • The fringe some portion of the optional xylem is delicately hued. This is known as sapwood. It supports in conduction of water and minerals. 

Plug Cambium 

  • Meristematic tissue which creates in the cortex area is called cork cambium or phellogen. 
  • The phellogen cuts off cells on the two sides. The external cells separate to shape stopper or phellem while the inward cells separate into auxiliary cortex or phelloderm. 
  • Phellogen, phellem and phelloderm are by and large called periderm. 
  • Because of movement of the cork cambium, pressure develops on the rest of the layers fringe to the phellogen. These layers continuously pass on and tumble off. 

Lenticels 

  • At specific locales, the phellogen cuts off firmly masterminded parenchymatous cells on the external side rather than plug cells. These parenchymatous cells before the long break the epidermis, framing a focal point moulded openings called lenticels. 
  • Lenticels license the trading of gases between the external climate and the inner tissue of the stem. 

Optional Growth in Roots 

  • The vascular cambium of the dicot root begins from the tissue found just underneath the phloem packs. A part of pericycle tissue present over the protoxylem structures a constant wavy ring. It step by step gets roundabout. Rest of the means are comparative as in dicot stem. 
  • Secondary development happens in stems and foundations of gymnosperms. No optional development happens in monocots. 

Questions 

Q1. Which kind of plant tissues are xylem and phloem? 

Answer: Xylem and phloem are the directing tissues of the vascular strands. Their primary job is in the transportation of food, minerals, and water. Xylem is the tissue which is liable for the vehicle of water in plants while the phloem is answerable for the exchange of food and supplements in the plant. These tissues are liable for the conduction of substances in plants through and through and accordingly, causes in shipping materials to and from top and base of the plant. 

Q2. Which plant tissues are liable for invigorating a plant and backing? 

Answer: Collenchyma is found in the hypodermis in dicot plants and might be oval, circular or polygonal fit as a fiddle. It comprises of cells which have a statement of cellulose, hemicellulose, and gelatin around the bend and offer mechanical help to the plant, helps in twisting and give rigidity to stem. 

Sclerenchyma is a dead, long, limited cells with thick and lignified cell dividers having a couple of various pits offer mechanical help and are financially significant. These are generally found in organic product mass of nuts, the husk of the coconut, seed layer of vegetables and jute and so on.

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