Notes And Study Material for Exam Papers

BIFACIAL LEAF: It is also called dorsiventral leaf. This leaf is more strongly illuminated on upper surface than on lower surface. This unequal illumination induces a difference in the internal structure between upper and lower sides. Its internal structure shows: (1)        Upper Epidermis This is single layer of cells with thick cuticle which checks excessive evaporation of water from the surface. It does not contains chloroplasts, stomata are also absent. (2)        Lower Epidermis This is also single layer but with a thin cuticle. It bears many stomata, two guard cells of which contain some chloroplast, none are present in the epidermal cells. Internal to each stomata is large cavity called respiratory cavity. Lower epidermis of leaf is meant for exchange of gases (oxygen and carbon dioxide) between the atmosphere and the plant body. Excess water also evaporates from lower epidermis. (3) ...

Secondary meristematic tissues are those which arise as new meristematic in non meristematic or permanent tissue, later at a certain stage of development. Sometimes the permanent tissues develop the power of division and form secondary meristems. Cork cambium forms the typical example of secondary meristem as it is developed from mature cells of epidermis, cortex of pericycle. Secondary meristems are generally lateral in position and give rise to secondary tissues which add to girth of the plant organ. The vascular cambium is stems are partly a secondary meristem. Cambium is a band of thin walled tissue lying between phloem and xylem. Its cells are arranged in radial rows and are roughly rectangular in shape, very small in size and very thin walled. Cambium is responsible for secondary growth in thickness of the plant body. In study herbs and in all shrubs and trees secondary growth takes place as a result of the formation of new (secondary) tissues in them. Secondary tissues are...

Vascular bundles are present in stele. The stele is the central column of Dicot stems and all roots surrounded by endodermis and consist of pericycle, vascular bundles, medullary rays and pith. Each bundle may be made up of both xylem tissue and phloem tissue with a cambium. Vascular bundles conduct water and raw food-material from roots to leaves and preparel food-material from leaves to storage organs and growing regions. Vascular bundles may be regularly arranged in a ring as in stems of most dicotyledons and in all roots, or they may be scattered in the ground tissue as in stems of Monocotyledons. A vascular bundle of Dicot stem consists of three kinds of tissues (1) Xylem or wood (2) Phloem or bast and (3) Cambium. Vascular bundles are radial when xylem and phloem form separate bundles lying on different radii alternating with each other as in roots. They are courjomt when xylem and phloem combine into one bundle. Conjomt bundles may collateral when xylem and phloem lie ...

Tissue is group cells of the same type or of mixed type having common origin and performing an identical function. Tissues may be meristematic and permanent. A simple tissue is made up of one type of cells forming homogenous or wniform mass. Simple tissue is of three kinds i.e. Parenchyma, Collenchyma and Sclerenchyma. (1)        Parenchyma Parenchyma consists of a collection of cells which are more or less equally expanded on all sides. Typical parenchymatous cells are oval, spherical or polygonal in shape. Their cells are thin and made of cellulose. They are usually living. Parenchyma is of universal occurance in all  soft parts of plants. Its function is mainly storage of food material. Parenchyma containing chloroplasts often called chlorenchyma, manufactures sugar and starch. Star like parenchyma with radiating arms leaving a lot of air cavities is called acrenchyma, as in the petiole of banana and canna and also in many aquat...

Xylem and phloem are called the conducting tissues. Xylem is meant to conduct water and mineral salts upward from root to the leaf and give mechanical strength to the plant body. Except wood parenchyma all other xylem elements are lignified thick walled and dead. Phloem as a whole is meant to conduct prepared food material from leaf to the storage organs and the growing regions. Elements of xylem are (a) Tracheids (b) Vessels or tracheae (c) wood fibres (d) wood parenchyma. (a)        Tracheids These are elongated tube like dead cells with hard thick and lignified walls and a large cell cavity. Their ends are commonly tapering or oblique. Their walls are provided with one or more rows of bordered pits. Tracheids may be annular, spiral, scalariform or pitted. In T.S they are angular polygonal or rectangular. Tracheids occur alone in wood of ferms and gymnosperms and in wood of angiosperms. They occur associated with vessels. Being lignified an...

Group of cells is called tissue. Group of cells may be similar or dissimilar with common origin and perform identical function. Meristematic tissue Meristos = divided. These are composed of cells that are in a state of division or retain the power of dividing. These cells are essentially alike being either spherical, oval or polygonal in shape without any intercellular spaces, their walls thin and homogenous; the protoplasm abundant and active with large nuclei and the vacuoles small or absent. Meristematic tissues may be apical and lateral. The apical meristem lies at the apex of the stem and the root and gives rise to primary permanent tissues while the lateral meristem e.g.: Cambium lies among masses of permanent tissues and gives rise to secondary permanent tissues. Permanent Tissues are composed of cells that have lost the power o dividing, having attained their definite form and size. They may be living or dead and thin walled or thick walled. Permanent tissues ...

BIFACIAL LEAF: It is also called dorsiventral leaf. This leaf is more strongly illuminated on upper surface than on lower surface. This unequal illumination induces a difference in the internal structure between upper and lower sides. Its internal structure shows: (1)        Upper Epidermis This is single layer of cells with thick cuticle which checks excessive evaporation of water from the surface. It does not contains chloroplasts, stomata are also absent. (2)        Lower Epidermis This is also single layer but with a thin cuticle. It bears many stomata, two guard cells of which contain some chloroplast, none are present in the epidermal cells. Internal to each stomata is large cavity called respiratory cavity. Lower epidermis of leaf is meant for exchange of gases (oxygen and carbon dioxide) between the atmosphere and the plant body. Excess water also evaporates from lower epidermis. (3)...

Secondary meristematic tissues are those which arise as new meristematic in non meristematic or permanent tissue, later at a certain stage of development. Sometimes the permanent tissues develop the power of division and form secondary meristems. Cork cambium forms the typical example of secondary meristem as it is developed from mature cells of epidermis, cortex of pericycle. Secondary meristems are generally lateral in position and give rise to secondary tissues which add to girth of the plant organ. The vascular cambium is stems are partly a secondary meristem. Cambium is a band of thin walled tissue lying between phloem and xylem. Its cells are arranged in radial rows and are roughly rectangular in shape, very small in size and very thin walled. Cambium is responsible for secondary growth in thickness of the plant body. In study herbs and in all shrubs and trees secondary growth takes place as a result of the formation of new (secondary) tissues in them. Secondary tissues are...

Vascular bundles are present in vascular tissue system and are distributed in the stele. The stele is the central column of Dicol stems. Each vascular bundle may be made up of both xylem tissue and phloem tissue with a cambium as in dicot stems or without cambium as in Monocot stems or of one kind of tissue xylem or phloem as in roots. Vascular bundle may be regularly arranged in a ring as in the stems of most dicotyledons and in all roots or they may be scattered in the ground tissue as in stems of Monocotyledons. Elements of Vascular Bundle Vascular bundle of Dicot stem when fully formed consists of there well defined tissues (1) Xylem or wood (2) Phloem or bast (3) Cambium. They have different kinds of tissue elements. (1)        Xylem or wood This lies towards the centre and is composed of (i) Trachae or vessels (ii) sone tracheids, (iii) a number of wood fibres and (iv) a small patch of wood parenchyma. Vessels are of various k...

Meristos equals to divided. These are composed of cells that are in a state of division or retain the power of dividing. These cells are essentially alike, being either spherical, oval or polygonal in shape without any intercellular spaces, their walls thin and homogenous, the protoplasm abundant and active with large nuclei and the vacuoles small or absent. Meristematic tissues may be apical and lateral. The apical meristem lies at the apex of the stem and the root and gives rise to primary permanent tissues. The meristems which are present from the embryomic stage and persist throughout the life of a plant are known as Primary Meristem. Secondary meristems are those which arise as new meristems in non meristematic or permanent tissue, later at a certain stage of development. On the basis of plane of cell division are three type of meristems called mass, plate and riibmeristem. On the basis of position in the plant body meristems may be apical, intercalary and lateral. Apical me...

Secondary growth is the increase in thickness due to formation of secondary tissues by the activity of cambium and cork cambium. It is found in dioct root and Gymnospermous roots, where it usually starts at very early stage. It is difficult to get the roots without secondary growth in most of the cases. (1)        ACTIVITY OF CAMBIUM Some of the cells of conjunctive tissues just beneath the phloem become meristematic and form strips of cambium. The number of strips formed depends upon number of phloem bundles present. In a diarch root two in triarch root and three in tetrarch root four such strips are formed. These strips extend between phloem and xylem and unite with pericyclic cells lying just outside protoxylum. The pericycle cells divide tangentially and form two layers of which the cells of inner layer also become meristematic and unite with the strips of cambia and thus continuous wavy band of cambium is formed extending down the phlo...

Secondary growth is the increase in thickness due to formation of Secondary tissues by the activity of cambium and Cork cambium. (1)        Activity of vascular cambium The meristem producing secondary xylem and phloem is called vascular cambium. As it occupies lateral position in the axis, it is called lateral meristem. Cambial cells differ from nomal meristems in being highly vacuolated. These occur in two forms, the fusiform initial which is much longer than wide and the ray initial which is almost isodiametric. Fusiform initials form axial system and ray initials from the radial system of zone of cambial initials. Former gives rise to axial system of secondary xylem and the latter to radial system. Formation of cambium ring: At the time of secondary growth the cells of medullary rays in a line with fascicular cambium become meristematic and form new strips of secondary meristems called interfascicular cambium. These strips joinstrips of...

Complex tissue is made up of more than one type of cells working together as a unit. Following are kinds of Complex tissue: (1)        Xylem Xylem or wood in conducting tissue and is composed of elements of different kinds (a) tracheids (b) vessels or tracheae (c) wood fibres and (d) wood parenchyma. Xylem as a whole is meant to conduct water and mineral salts upward from the root to the leaf and to give mechanical strength to the plant body. Except wood parenchyma all other xylem elements are lignified, thick walled and dead. (a) Tracheids: These are elongated tube like dead cells with hard, thick and lignified walls and a large cell cavity. Their ends are commonly tapering or oblique. Their walls have one or two rows or bordered pits. Tracheids may be annular, spiral, scalarinform or pitted. Tracheids occur alone in the wood of ferms and gymneosperms where as in wood of angiosperms they occur associated with vessels. Tracheids give stre...

Meristematic tissues Meristos = divided. They are composed of cells that are in a state of division or retain the power of dividing. These cells are essentially alike, being either spherical, oval or polygonal in shape without any intercellular spaces; their walls thin and homogenous; the protoplasm abundant and active with large nuclei and the vacuoles small or absent. Meristematic tissues may be apical and lateral: (a) The apical meristem lies at the apex of the stem and the root and gives rise to primary permanent tissues while (b) The lateral meristem e.g.: Cambium lies among masses of permanent tissues and gives rise to secondary permanent tissues. Permanent Tissues: These are composed of cells that have lost the power o dividing, having attained their definite form and size. They may be living or dead and thin walled or thick walled. Permanent tissues are formed by differentiation of the cells of the meristems (apical and lateral) and may be primary and seco...

Vegetative characters: Habit: Plant varies in habit. There are all types of plants like herbs, shrubs and trees. Root: It is usually tap root branched, in some adventitious roots may be present. Stem: Aerial, erect, in some semi-prostrate e.g. Malva, Sida, Hibiscus sps, herbaceous above and woody below, completely woody in trees, solid or fistular, branched, usually hairy. Leaf: Cauline and ramal, alternate, stipulate, stipules caduious or deciduous, simple, in some compound ovate multi-costate reticulate venation. Floral Characters: Influence usually solitary terminal or solitary axillary and in some raceme. Flower: Bractiate or ebractiate, bracteolate or ebractedate, regular, complete bisexual, mostly hypogynous, cyclic, variously coloured. Epicalyn lobes 3-12 free of fused, green calyxsapals 5 gamosepalous, campanilate, tubular or infundibuliform sometimes persistent, green, velvate. Petals 5, twisted, stamens numerous monadelphous forming a staminal tube fused at the base with ...

Solanacea or Potato family is best known family. Plants are found widely in temperate regions and very abundant in tropical countries plants of the family are potato (Solanum tuberosum), Tomato (hycopersicum esculentum), egg plant (Solanum melongena), Red pepper (capsicum frutescens), tobacco (Nicotiana tabacum) and solanum nigrum (make). Vegetative characters: Plants are usually herbs or climbing vines in temperate zones but in tropics many shrubby forms are found and a few trees. Production of underground tuber, like potato is expected. Root - tap and branched. Stem-harbaceous erect, branched, hairy or prickly. Underground are potatoes forming tubers. Leaf is alternate in the vegetative and opposite in the floral region, simple but much divided, sometimes pinnatisect in few species, exstipulate. Anatomically the stem shows bi-collateral bundles. Floral Characters: Inflorescence: Usually on axillary cyme or combination of cymes, sometimes helicoids. Flower: Pentamerous, bisexual, r...

Englar and Prantl system of classification:  Two German botanists Adolph Englar (1844 – 1930) and Karl Prantl (1848 – 1893) published their classical treatise “Die Naturalichen Pffanzen families” covering the entire plant kingdom nearly half a century ago (1887 – 1909). While the authors named did much of the work o the flowering plants many sections throughout the plant kingdom were assigned to other specialists. Englar and Prantl system is a development of that Eichler and follows it in many respects. It has replaced Benthem and Hooker system in the continent of Europe and America as the latter is defective in as much as the families under Monochlamydeae show close affinities with those placed in the other groups such as Polypetalae. According to Englers’ system Monochlamydeae is completely abolished as such and its families are distributed in large series called Archiochlamydae. This system now dominates the field of systematic Botany, though not to the exclusion of others. S...