These MP Board Class 11th Biology Notes for Chapter 6 Anatomy of Flowering Plants help students to get a brief overview of all the concepts.
MP Board Class 11th Biology Notes Chapter 6 Anatomy of Flowering Plants
(A) Plant Tissue And Anatomy
→ A group of cells having a similar structure and function is called a tissue.
→ In plants two types of tissues are present: (i) Meristematic tissue and (ii) Permanent tissue.
→ The tissues that are capable of cell division are called meristematic tissue.
→ There are three groups of meristematic tissues : (i) Apical meristem, (ii) Intercalary meristem, (iii) Lateral meristem.
→ Apical meristem is found in the tips of shoot and roots, intercalary meristem occurs below the nodes and lateral meristem occurs on the lateral portion of the plant body.
→ Tissues which have no capacity to divide are called permanent tissues.
→ Callose is a polysaccharide which lines the pores of sieve plate.
→ The thickening of lignin and suberin on the inner tangential and radial walls of endodermis is called casparian strip.
→ The xylem having protoxylem towards the centre of the axis is called endarch.
→ The xylem having protoxylem towards periphery and metaxylem towards the centre is called
exarch.
→ The endodermal cells opposite the protoxylem groups that lack the thickening of lignin and suberin are called passage cells.
→ Tracheids are the elongated cells with tapering ends found in xylem of gymnosperms and angiosperms.
→ Vessel is a pipe like structure representing rows of cells, placed one above the other, in the xylem tissue.
→ Parenchyma and collenchyma are the living tissues of plant body.
→ The xylem of stem is endarch whereas it is exarch in roots.
→ Xylem is made up of tracheids, vessels, xylem fibres, and xylem parenchyma.
→ Xylem is the conductive tissue which plays a vital role in the conduction of water and minerals.
→ Phloem is made up of sieve tube, companion cell, phloem fibre and phloem parenchyma.
→ Phloem plays an important role in the conduction of organic food manufactured by leaves.
→ Xylem and phloem are the conductive tissues of plant which are collectively called as vascular bundle.
→ Simple tissues consist of single type of cells which are similar in origin, morphology and functions. Simple tissue may be (i) Parenchyma, (ii) Collenchyma, (iii) Sclerenchyma.
→ Parenchymatous cells act as storage tissue for food starch, fats, oil and proteins.
→ Collenchyma provides strength to the organs.
→ Sclerenchyma has thickened, usually lignified cell walls, which acts as supporting tissue.
→ Calyptrogen is a constituent of root apical meristem which occurs in monocots and is meant for producing the root cap.
→ The vascular bundle in which xylem and phloem are found in separate bundles present on different radii is called radial V.B. It is the characteristic of roots.
(B) Secondary Growth
→ Secondary growth is the increase in the girth of stems and roots.
→ Tissues formed from primary meristem are called as primary tissues, whereas tissues formed from secondary meristem are called as secondary tissues.
→ Increase in the girth of stems and roots due to secondary tissues is called as secondary growth.
→ Secondary growth is the characteristic feature of dicotyledonous stems and roots.
→ Except few cases, secondary growth is absent in monocotyledonous stems and roots.
→ Secondary growth takes place due to the activity of cambium and cork cambium.
→ Cambium present between xylem and phloem is called fascicular cambium.
→ Cambium present between two vascular bundles in ground tissue is called interfascicular cambium.
→ Fascicular and interfascicular cambium together constitute cambium ring.
→ Cambium ring cuts off secondary phloem on outer surface and secondary xylem on its inner surface.
→ During secondary growth, cells of the outermost layer of cortex become meristematic to produce cork cambium.
→ During secondary growth due to increase in the girth of stems and roots, the epidermis ruptures and cells become dead to produce bark.
→ Cork cambium cuts off cork cells on outer surface and secondary’ cortex on inner surface.
→ Cork cells and secondary cortex together constitute cork which is used for making plug of bottles.
→ Secondary xylem forms the maximum part of wood.
→ Lenticels are the pores on the bark of stem, composed of loosely arranged parenchymatous cells having intercellular spaces for gaseous exchange.
→ Secondary wood formed during a single year or one growth period is called annual ring.
→ The age of the plant can be calculated by the counting of annual ring.
→ The bladder like out growths of parenchyma, through the pores in the lateral walls of xylem vessel cause plugging of them and are called as tyloses.
→ Heartwood is the dark coloured wood in the centre and is dead. It contains oils, gums, resins, tannins, etc.
→ Heartwood is more durable and resistant to micro-organisms and insects. It is good for furniture.
→ Sapwood is the peripheral light coloured living wood responsible for conduction of materials.
→ Sapwood is less durable and resistant to micro-organisms and insects. Good for fuel.
→ Heartwood is a porous wood as it has vessels.
→ Early wood is formed during favourable seasons of spring and summer when cambium is active and produce large vessels or tracheids.
→ Late wood is produced during adverse conditions of climate (autumn and winter) in which tracheids and vessels are smaller.
→ Wood is the name of secondary xylem of the stems and main roots but the term wood can also be used for all types of xylem.
→ During leaf fall, cork cambium is formed in the leafbase which results in the formation of an abscission layer.
→ The cells formed on inner surface of the phellogen are called phelloderm or secondary cortex.
→ Dracena is a monocot plant, whose stem exhibit abnormal secondary growth.