Here students can locate TS Inter 1st Year Botany Notes 12th Lesson Histology and Anatomy of Flowering Plants to prepare for their exam.
TS Inter 1st Year Botany Notes 12th Lesson Histology and Anatomy of Flowering Plants
→ Study of different tissues in the plant body is called Histology.
→ Study of internal structures (arrangement of various tissues) of plants is called Anatomy.
→ Different organs in a plant show differences in their internal structure.
→ Internal structures also show adaptations to diverse environments.
→ Katherine Esau
- Katherine Esau was horn in Ukraine in 1898.
- She reported in her early publications that the curly top virus spreads through a plant via the food conducting or phloem tissue.
- Dr Esau’s Plant Anatomy published in 1954 took a dynamic, developmental approach designed to enhance one’s understanding of plant structure and had enormous impact world wide, literally bringing about a revival of the discipline. The Anatomy of seed plants by Katherine Esau was published in 1960. It was referred to as Webster’s of plant biology – it is encyclopediac.
→ Internal Morphology deals with the study of internal structure of different plant organs. It has two branches they are Histology and Anatomy.
→ Histology is the study of different tissues present in the plant body.
→ Anatomy deals with the study of gross internal details of plant organs like root, stem, leaf, flower, etc.
→ Tissues are functional units of an organ. Tissues are groups of cells having similar, function and origin.
→ Meristems are localised growth regions of the plant producing,new tissues and organs throughout its life period. Based on origin – 2 types – primary meristem, secondary meristem. Based on position – 3 types – apical, intercalary and lateral meristems.
→ Permanent tissues have mature cells adapted to specific function.
→ Simple tissues have similar kinds of cells.
→ Parenchyma is a fundamental living tissue with intercellular spaces.
→ Collenchyma is a simple living mechanical tissue.
→ Sclerenchyma is a simple dead mechanical tissue with lignified walls.
→ Tissue systems are three types. They are – epidermal, ground and vascular.
→ The epidermal tissue systems are made up of epidermal cells, stomata and the epidermal appendages.
→ 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.
→ The general plant internal structure is similar in both dicot and monocot roots.
→ Root TS shows 3 regions – epidermis, cortex and stele.
→ Exodermis contains suberised cells prevents leakage of water.
→ General cortex is made up of parenchyma.
→ Epidermis is outermost layer with unicellular root hairs. Cuticle & stomata are
→ Exodermis shows casparian bands.
→ Stele consists of pericycle, vascular bundles, conjunctive tissues and pith.
→ Pericycle is a single layered parenchymatous cells. Pericycle gives lateral roots.
→ Vascular bundles are separate, radial, alternate and closed. Xylem is exarch.
→ Stele is monarch to octarch, generally tetrarch in dicot root and polyarch in monocot root.
→ Pith is either scanty or absent in dicot root. It is large and well developed in monocot root.
→ Conjunctive tissue is present between xylem and phloem strands.
→ A typical dicot stem consists of epidermis, cortex and stele. A typical monocot stem shows epidermis, hypodermis, ground tissue and vascular bundles.
→ Epidermis is a uniseriate protective layer covered with cuticle. Stomata help in exchange of gases.
→ Hypodermis is collenchymatous in dicot stem and sclerenchymatous in monocot stem.
→ General cortex in dicot stem and ground tissue in monocot stem are parenchymatous.
→ Endodermis is distinct only in dicot stem with casparian strips.
→ Stele is eustele in dicot stem and atactostele in monocot stem.
→ Vascular bundles are few and arranged in a ring inside pericycle in dicot stem. They are numerous and scattered in the ground tissue in monocot stem.
→ Vascular bundles are conjoint, collateral and endarch They are open in dicot stem and closed in monocot stem.
→ Distinct pith and medullary rays are present in dicot stem.
→ Dicot leaf is dorsiventral and monocot leaf is isobilateral.
→ Epidermis covers adaxial and abaxial surfaces of the leaf. Cuticle and stomata are present.
→ Mesophyll is differentiated into upper palisade and lower spongy tissues in dorsiventral leaf. It is undifferentiated and homogeneous in isobilateral leaf.
→ Vascular bundles are collateral and closed. Xylem is on upper side and phloem on lower side. Vascular bundle is covered with bundle sheath.
→ In Monocot leaf upper epidermis shows bulliform or motor cells.
→ Secondary growth results in increase in girth by addition of secondary tissues.
→ Interfascicular and intrafascicular cambia together form vascular cambium.
→ Vascular cambium forms secondary xylem inside and secondary phloem on the exterior.
→ Cork cambium develops from cortical region. It produces cork towards outside and secondary cortex on the inner side.
→ Secondary xylem or wood forms the bulk of tree. Production of secondary xylem is affected by seasonal change.
→ Autumn wood and spring wood formed in one year together constitute annual ring.
→ Wood in the centre of the tree ceases to perform the function of conduction and is blocked by gums, resins, tyloses etc. It is called heartwood. Outer lighter sapwood is functional wood.
→ Cork is a dead tissue containing suberised cells.
→ Phellogen (cork cambium), phellem (cork) and phelloderm (secondary cortex) constitute periderm.
→ Lenticels are lens shaped openings found in the cork for gaseous exchange.
→ All tissues outside the vascular cambium constitute bark.