PST Level 5 Semester 2

NTA Level 5 • Semester 2 • PST05210 Extraction of Active Medicinal Principles from Natural Sources Basic Pharmacognosy • Source Session/Topic 14 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 14: Extraction of Active Medicinal Principles from Natural Sources Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Definition of terms • List types of extracts • Explain factors affecting extraction process • Explain Mechanism of solvent extraction • Outline properties and types solvents • Explain methods for extraction of active drugs Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD Projector and laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning | | | | |Tasks | |2 |10 minutes |presentation |Definition of terms | |3 |05 minutes |Presentation |Types of extracts | |4 |30 minutes |Presentation |Properties and types of | | | |buzzing |solvents | |5 |15 minutes |Presentation |Mechanism of Solvent | | | | |Extraction | |6 |05 minutes |Presentation |Factors affecting | | | | |extraction | |7 |40 minutes |Presentation |Methods of extraction | | | |Small group Discussion| | |8 |05 minutes |Presentation |Key Points | |9 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Objectives (05 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Definition of terms (10 Minutes) • Extraction is the method of removing active constituents from a solid or liquid by means of liquid solvent. o The separation of medicinally active portions of plant or animal tissues from the inactive or inert components by using selective solvents. o In this method the wanted components are dissolved by the use of selective solvents known as menstrum & undissolved part is a marc, after the extraction unwanted matter is removed. • Extract: Extracts can be defined as preparations of crude drugs which contain all the constituents which are soluble in the solvent. • Marc: Solid residue obtain after extraction Menstruum • Solvent is a liquid substance capable to dissolve other substances (solutes) without chemical changes. o (The term “Solvents” refers to a class of chemical compounds described by function – the term derives from Latin, meaning roughly to “loosen.” In chemistry, solvents – which are generally in liquid form – are used to dissolve, suspend or extract other materials, usually without chemically changing either the solvents or the other materials Step 3: Types of Extracts (05 minutes) • Type of extracts o Dry extract (Tab, cap.) E.g. belladonna extract o Soft (Ointment, suppository) E.g. glycerrhiza extract. o Liquid: As tincture. STEP 4: Properties and Types of Solvents (30 minutes) |Activity: Buzzing (10 minutes) | | | |DIVIDE students into small manageable groups | | | |ASK students to discuss on the following question | | | |What are types of solvents? | | | |ALLOW students to discuss for 15 minutes | | | |ALLOW few groups to present and the rest to add points not | |mentioned | | | |CLARIFY and SUMMARIZE by using the contents below | • Types of Solvent o Molecular structure of solvents o Inorganic solvents o Organic solvents • Molecular structure of solvents o Molecular structure of solvents, Ability of a substance to dissolve another substance is determined by compatibility of their molecular structures (like dissolves like). ▪ Types of molecular structures of the solvents are as follows: • Polar protic solvents o A polar protic molecule consists of a polar group OH and a non- polar tail. The structure may be represented by a formula R-OH. Polar protic solvents dissolve other substances with polar protic molecular structure. Polar protic solvents are miscible with water (hydrophilic). Examples of polar protic solvents: ▪ Water (H-OH), ▪ Acetic acid (CH3CO-OH) ▪ Methanol (CH3-OH), ▪ Ethanol (CH3CH2-OH), ▪ n-propanol (CH3CH2CH2-OH), ▪ n-butanol (CH3CH2CH2CH2-OH). • Dipolar aprotic solvent o Dipolar aprotic molecules possess a large bond dipole moment (a measure of polarity of a molecule chemical bond). They do not contain OH group. Examples of dipolar aprotic solvents:\ ▪ Acetone ((CH3)2C=O), ▪ Ehyl acetate (CH3CO2CH2CH3), ▪ Dimethyl sulfoxide ( (CH3)2SO ), ▪ Acetonitrile (CH3CN), ▪ Dimethylformamide ( (CH3)2NC(O)H ). • Non-polar solvents o Electric charge in the molecules of non-polar solvents is evenly distributed, therefore the molecules have low dielectric constant. Non-polar solvents are hydrophobic (immiscible with water). Non-polar solvents are liphophilic as they dissolve non- polar substances such as oils, fats, greases. Examples of non-polar solvents: ▪ carbon tetrachloride (CCl4), ▪ benzene (C6H6), ▪ and diethyl ether ( CH3CH2OCH2CH3), ▪ hexane (CH3(CH2)4CH3), ▪ methylene chloride (CH2Cl2). • Inorganic solvents o The most popular inorganic (not containing carbon) solvents are o water (H2O) and aqueous solutions containing special additives (surfacants, detergents, PH buffers, inhibitors). o Other inorganic solvents are liquid anhydrous ▪ Ammonia (NH3), ▪ concentrated sulfuric acid (H2SO4), ▪ sulfuryl chloride fluoride (SO2ClF). • Organic solvents o Oxygenated solvent is an organic solvent, molecules of which contain oxygen. Oxygenated solvents are widely used in the paints, inks, pharmaceuticals, fragrance sectors, adhesives, cosmetics, detergents, food industries. Examples of oxygenated solvents: ▪ Alcohols, ▪ Glycol ethers, ▪ Methyl acetate, ▪ Ethyl acetate, ▪ Ketones, ▪ Esters, ▪ Glycol ether/esters STEP 5: Mechanism of Solvent Extraction (15 minutes) • Mechanism of solvent extraction o Dissolution of extractive substances out of disintegrated cells. o Dissolution of extractive substances out of intact plant cell by diffusion (requires steeping and swelling) o Penetration of the solvent into the plant cells and swelling of the cells. o Diffusion of the dissolved extractive substances out of the cell. o Plant constituents are usually contained inside the cells. o Therefore, the solvent used for extraction must diffuse into

NTA Level 5 • Semester 2 • PST05210 Collection, Processing and Storage of Medicinal Plants Basic Pharmacognosy • Source Session/Topic 13 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 13: Collection, Processing and Storage of Medicinal Plants Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • List methods for collection of medicinal drugs • Explain the importance of processing medicinal plants • Explain methods of drying of crude drugs • Explain storage of medicinal plants Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • Computer and LCD Projector SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |30 minutes |Presentation |Collection of Medicinal Plants | |3 |45 minutes |Presentation |Processing of Crude Drugs | |4 | |Small group |Storage of Crude Drugs | | |30 minutes |Discussion | | | | |Presentation | | |5 |05 minutes |Presentation |Key Points | |6 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Collection of Medicinal Plants (30 minutes) • Collection refers to harvesting or obtaining drugs from medicinal plants • Drugs may be collected from wild or cultivated plants • Collection may be done by skilled or unskilled labour • Collection from cultivated plants is more advantageous and ensures sustainability of medicinal plants • In some cases, pharmacopoeias specify collection of certain drugs from cultivated species such as Fennel, ginger, cinnamon and opium • Some drugs e.g. senna, tragacanth and others may be collected from wild or cultivated species. • Active constituents in plants vary in amount and nature throughout the year, so collection should be done at the right time when active constituents are at the highest levels. For instance, o Time (season) of the year ▪ Rhubarb contains high levels of anthranols in winter and high levels of anthraquinones in summer. Anthranol are oxidized to anthraquinones in summer o Time of the day ▪ Digitalis is collected in the afternoon contains more cardiac glycosides ▪ Solanaceous leaves collected in the morning have more alkaloids o Stage of maturity ▪ In Eugenia caryophyllus, buds contain high oil but mother “blown” cloves contain very little oil ▪ Vanilla has highest levels of vanillin 8 months after flowers open • General factors to consider when harvesting/collecting drugs from medicinal plants; o Underground organs are collected when aerial parts die down o Leaves are collected when flowers are beginning to open o Flowers are collected in dry weather and just before they fully expand e.g. cloves o Fruits and seeds are collected when fully mature but unripe o Barks are collected in damp weather o Unorganized drugs are collected in dry weather o Leaves, flowers and fruits should not be collected when covered with dew or rain o Discoloured or parts attacked by insects should not be collected o Large organs should be sliced soon after collection to facilitate drying o Limits of unwanted parts in desired parts must be considered when collecting medicinal plants e.g. aerial stems in rhizomes STEP 3: Processing of Crude Drugs (45 minutes) • After collection, drugs should be processed to meet various requirements such as market requirements • Processing of crude drugs is important in order prevent deterioration • Processing of drugs from natural sources depends on morphological nature, constituents, geographical source and other related factors • Drying is an important aspect of processing crude drugs o There various reasons for drying drugs obtained from medicinal plants ▪ To decrease size and weight i.e. to facilitate packing, transport and storage ▪ To facilitate powdering ▪ To prevent enzyme action ▪ To prevent microbial growth ▪ To prevent degradation of active constituents o Enzyme action may be desired or undesirable after collection ▪ When enzyme action is desired after collection e.g. in vanilla pods, gentian roots and cocoa seeds, the collected drug is dried slowly at moderate temperature ▪ Drying is done as soon as possible after harvesting when enzyme reaction is not desired e.g. digitalis leaves o Methods of Drying o There are various methods that are used in drying crude drugs o The choice of a drying method depends on physical characteristics of the plant and chemical characteristics of the active constituents ▪ Air Drying • Sun Drying o Is done when drugs are not adversely affected by excessive sunlight. o Drugs are dried in thin layers and tuned over occasionally o Drugs dried in this way include clove and cardamom • Shade Drying o Done when sunlight causes discoloration and warping/shrivelling of the drugs e.g. cinnamon ▪ Artificial Drying • Artificial source of heat is used in the drying process • Drying in the oven (oven drying) is the commonest methods used in artificial drying • Artificial drying is more accepted and more rapid than air-drying • Artificial drying is more suitable for use in the wet weather • Drying temperature is governed by constituents o Generally, leaves, herbs and flowers are dried between 20-40oC, barks and roots: 40-65oC • When done rapidly, the drugs retain colour and aroma ▪ Vacuum Drying • It is also done in oven, but at low temperature • Low pressure ensures rapid and complete drying • It is an expensive method and thus reserved for expensive drugs or drugs which cannot be sufficiently dried by other methods ▪ Lyophilisation • Involves freezing of the drug and then evaporation under low pressure • Very suitable method for drugs that are very sensitive to heat • The resulting product is a fine powder • This method is used for drying biological fluids, enzymes, proteins

NTA Level 5 • Semester 2 • PST05210 Indole and Imidazole Alkaloids Basic Pharmacognosy • Source Session/Topic 24 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 24: Indole and Imidazole Alkaloids Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define indole and imidazole alkaloids • Explain natural sources and uses of alkaloid Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • Computer and LCD Projector SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |15 minutes |Presentation |Natural Sources and Uses of | | | | |Pilocarpus | |3 |15 minutes |Presentation |Natural Source and Uses of Vinca | | | |Buzzing |Alkaloids | |4 |15 minutes |Presentation |Natural Source and Uses of Ergot | | | | |Alkaloids | |5 |15 minutes |Presentation |Natural Source and Uses of Nux | | | | |Vomica | |6 |15 minutes |Presentation |Natural Source and Uses of Calabar| | | | |Beans | |7 |15 minutes |Presentation |Natural Source and Uses of | | | | |Rauwolfia | |8 |15 minutes |Presentation |Natural Source and Uses of Yohimbe| | | | |Bark | |9 |05 minutes |Presentation |Key Points | |10 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning tasks and clarify ASK students if they have any questions before continuing. STEP 2: Natural Sources and Uses of Pilocarpus (15 minutes) • Definition o Pilocarpus consists of imidazole alkaloids obtained from leaves of closely related species of Pilocarpus jaborandi and other species of the genus Pilocarpus, family Rutaceae o It is also known as Jaborandi • Constituents o Pilocarpine o Isopilocarpine o Pilocarpidine o Pilosine o Pseudopilocarpine o Isopilosine • Uses o Used in form of Pilocarpine Hydrochloride o It is a physiological antagonist of Atropine o Used in ophthalmic practices e.g. treatment of glaucoma o Causes contraction of pupil of the eye STEP 3: Natural Source and Uses of Vinca Alkaloids (15 minutes) • Definition o Vinca alkaloids are oncolytic indoline alkaloids obtained from dried whole plant of Catharanthus roseus, family Apocynaceae • Constituents o Leurocristine (vincristine) o Vincaleukoblastine (vinblastine) ▪ Vinblastine is converted into vincristine by chemical reactions or by microbial N-demethylation using Streptomyces albogriseolus |Activity: Buzzing (5 minutes) | | | |ASK students to pair up and buzz on the following question for 2 | |minutes | | | |What are uses of Vinca Alkaloids? | | | |ALLOW few pairs to respond and let other pairs to add on points | |not mentioned | | | |WRITE their response on the flip chart/board | | | |CLARIFY and SUMMARIZE by using the content below | • Uses o Vinblastine – treatment of generalized Hodgkin’s disease, lymphocytic lymphoma, histiocytic lymphoma, advanced testicular carcinoma, kaposi’s sarcoma, choriocarcinoma and breast cancer unresponsive to therapy o Vincristine – treatment of acute lymphocytic leukemia in combination therapy in Hodgkin’s disease, ymphosarcoma, reticulum cell sarcoma, neuroblastoma and Wilm’s tumour STEP 4: Natural Sources and Uses of Ergot Alkaloids (15 minutes) • Definition o Ergot is the dried sclerotium of a fungus Claviceps purpurea, arising in the ovary of the rye, Secale cereal, family Hypocreaceae o The sclerotium arises in the ovary of the rye – secale cereale • Constituents o Contains water soluble and water insoluble alkaloids o Water soluble: ▪ Ergometrine ▪ Ergonovine ▪ Ergometrinine o Water insoluble: ▪ Ergotamine ▪ Ergotaminine ▪ Ergotoxine o Derivatives of lysergic acid ▪ Lysergic acid diethylamide (LSD) • Uses of ergot alkaloids o Ergometrine is used to control postpartum haemorrhage o Ergometrine produces oxytocic effects o Ergotamine and semi-synthetic dihydrohydroxy ergotamine are employed as specific analgesic for treatment of migraine (caffeine enhances absorption) o Lysergic acid derivative, LSD is a psychomimetic (a potent hallucinogen) controlled under narcotics STEP 5: Natural Sources and Uses of Nux vomica (15 minutes) • Definition o Nux vomica are dried, ripe seeds of Strychnous nux-vomica, family Loganiaceae • Constituents o The Main indole alkaloids are; ▪ Strychnine ▪ Brucine • Strychnine is more physiologically active than brucine • Strychnine is present in the inner part of the endosperm while brucine is in the outer layers ▪ Other alkaloids are: • α-colubrine, β-colubrine, vomicine, pseudostrychnine and isostrychnine o The drug also contains 3% fixed oils, glycoside – loganin • Uses o It stimulates peristalsis in chronic constipation and is often combined with cascara and other laxatives o Bitter stomachich and tonic (increases gastric juice to improve appetite and digestion) o Improves the pulse and raises blood pressure o At higher doses it is a lethal poison o Brucine is used commercially as an alcohol denaturant (as it is extremely bitter) STEP 6: Natural Sources and Uses of Calabar Beans (15 minutes) • Definition o Calabar beans are dried seeds of Physostigma venonosum, family Leguminosae o The seeds are extremely hard • Constituents o Physostigmine, o Isophysostigmine, o Physovenine o Eserinmine o Geneserine • Uses o A reversible inhibitor of cholinesterase thus enhancing the effect of endogenous Acetylcholine o It is used systematically as an antidote for atropine poisoning and other anticholinergic drugs o Used in ophthalmology to contract the pupil, to combat mydriasis o It is used in the treatment of glaucoma ▪ It decreases intra-ocular pressure caused by increased outflow of the aqueous humour STEP 7: Natural Sources and Uses of Rauwolfia (15 minutes) • Definition o Rauwolfia consist of dried rhizome and roots of Rauwolfia serpentine, family Apocynaceae o The drug is commonly known as Indian snake root o The African rauwolfia consists of dried roots of Rauwolfia vomitoria widely distributed in tropical Africa • Constituents o Major alkaloids are: ▪ Reserpine ▪ Resinnamine o

NTA Level 5 • Semester 2 • PST05210 Pharmaceutical Barks Basic Pharmacognosy • Source Session/Topic 11 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 11: Pharmaceutical Barks Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define a bark • Explain the structure of a bark • Explain the curvatures of a bark Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • Computer and LCD Projector SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning tasks | |2 |10 minutes |Presentation |Introduction to | | | |Buzzing |Pharmaceutical Barks | |3 |20 minutes |Presentation Small |Structure of Pharmaceutical | | | |group Discussion |Barks | |4 |15 minutes |Presentation |Barks Curvatures | |5 |05 minutes |Presentation |Key Points | |6 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Introduction to Pharmaceutical Barks (10 minutes) |Activity: Buzzing (5 minutes) | | | |ASK students to pair up and buzz on the following question for 2 | |minutes | | | |What is a bark? | | | |ALLOW few pairs to respond and let other pairs to add on points not | |mentioned | | | |WRITE their response on the flip chart/board | | | |CLARIFY and SUMMARIZE by using the content below | • The bark is the outer surface of the stem and is made of tissues produced by the cambium. The bark lies outside the cambium. STEP 2: Structure of Pharmaceutical Barks (20 minutes) |Activity: Small Group Discussion (15 minutes) | | | |DIVIDE students into small manageable groups | | | |ASK students to discuss on the following question | | | |Describe the structure of a bark | | | |ALLOW students to discuss for 15 minutes | | | |ALLOW few groups to present and the rest to add points not mentioned| | | | | |CLARIFY and SUMMARIZE by using the contents below | • A young bark is composed of the following tissues; o Epidermis ▪ A layer of closely fitting cuticularized cells with occasional stomata o Primary cortex ▪ A zone usually consisting of chlorophyll-containing collenchyma and parenchyma o Endodermis ▪ Inner layer of cortex, frequently containing starch o Pericycle ▪ May be composed of parenchyma or fibres, groups of fibres often occur opposite each group of phloem o Phloem: Consisting of sieve tubes, companion cells and phloem parenchyma separated by radially arranged medullary rays o Activity of the cambium and cork cambium or phelogen modifies the structure of the young bark o Pericycle is ruptured o Phelogen produces secondary cortex or phelloderm o Periderm is formed o Lenticels replace stomata for gaseous exchange o The fully matured barks have two parts; the outer bark and the inner bark o But in presentation for the market in some drugs only the inner bark is presented e.g. in cinnamon o The bark shows certain characteristics that are of diagnostic importance; ▪ Origin of the bark ▪ Size and shape of the bark ▪ Fracture of the bark STEP 4: Bark Curvatures (15 minutes) • Natural curvature of the bark increases when the bark is removed from the tree and dried • Large pieces of trunk bark, especially if subjected to pressure may be nearly flat • Commercial bark is presented for the market in various curvatures; o Flat o Curve o Channelled o Single quill o Double quill o Compound quill STEP 6: Key Points (5 minutes) • The barks consist of all tissues outside the cambium • The bark is divided into inner bark and outer bark • A young bark differs from bark produced after secondary growth STEP 7: Evaluation (5 minutes) • What is a bark? • Mention curvatures of barks? • What are the structures present in a bark? References Trease, G. E., Evans, W. C., & Evans, D. (2009). Trease and Evans pharmacognosy. London: Saunders. Joanne Barnes et al (2002), Herbal medicines 3rd Edition: Pharmaceutical Press Wallis, T. E. (2005). Textbook of pharmacognosy. New Delhi: CBS. Robbers, J. E., Speedie, M. K., Tyler, V. E., & Tyler, V. E. (1996). Pharmacognosy and pharmacobiotechnology. Baltimore: Williams & Wilkins. Heinrich, M., Kinghorn, A. D., Maizels, D., Gibbons, S., & Phillipson, J. D. (2012). Fundamentals of pharmacognosy and phytotherapy. Edinburgh: Churchill Livingstone/Elsevier. ← Previous TopicNext Topic →View all Basic Pharmacognosy topicsOpen Complete Full Notes PDF / OFFLINE NOTES Unataka kutumiwa notes hizi kupitia WhatsApp?Kwa notes zilizopangiliwa vizuri kwa kusoma offline au PDF, bonyeza kitufe hapa chini. Ujumbe wenye Level, Semester, Module na Topic utaandaliwa moja kwa moja.TUMIWA NOTES WHATSAPP WhatsApp: 255620339260

NTA Level 5 • Semester 2 • PST05210 Morphology of the Seed Basic Pharmacognosy • Source Session/Topic 10 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 10: Morphology of the Seed Total Session Time: 60 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define a seed • Describe the structure of a seed Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD projector and Laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |10 minutes |Presentation |Definition of a Seed | | | |Brainstorming | | |3 | |Small group |Structure of a Seed | | |35 minutes |discussion | | | | |Presentation | | |4 |05 minutes |Presentation |Key Points | |5 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Definition of a Seed (10 minutes) |Activity: Brainstorming (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What is a seed? | | | |ALLOW few students to respond? | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARIZE by using the content below | • Seed is the structure formed by plants from a ripened ovule after fertilization • There numerous sizes and shapes of seeds • Seeds are formed within a fruits of gymnosperm and angiosperms • Seeds may be formed from orthotropous ovules, campylotropous or anatropous ovules STEP 3: Structure of a Seed (35 minutes) |Activity: Small Group Discussion (10 minutes) | | | |DIVIDE students into small manageable groups | | | |ASK students to discuss on the following question | |Write down the external structures found on a seed | | | |ALLOW students to discuss for 15 minutes | | | |ALLOW few groups to present and the rest to add points not | |mentioned | | | |CLARIFY and SUMMARIZE by using the contents below | • Basic parts of a seed are the embryo, endosperm and the seed coat External structures of a seed o Seed coat ▪ Most seeds have two seed coats ▪ Testa (the outer seed coat) • Outer most protective layer of the seed –form the seed coat • Protects the seed • Thickness varies with type of seed ▪ Tegmen • The inner seed coat o Funicle or stalk ▪ A structure that attaches the seed to the placenta o Micropyle ▪ An opening that marks position of the radicle o Hilum ▪ Scar left by the funiculus (attachment to the embryo) o Raphe ▪ Fibrovascular tissue formed by adhesion of funicle and testa o Aril ▪ Expansion of placenta or funicle over the surface of the seed ▪ Formed in some seeds o Elaiosome ▪ Fleshy structures rich in lipids and proteins attached to the seed o Caruncle or Strophiole ▪ A structure that arises from the testa near the hilum • Internal structures of a seed o Embryo ▪ The immature plant within the seed from which a new plant grows • Made up of cotyledons o One cotyledon in monocotyledons plants o Two cotyledons in almost all dicotyledons and two or more in gymnosperms • Has radicle and plumule ▪ Endosperm • A tissue that forms beginning of food storage of a plant • Consists of two parts, one part stores starch and the other part stores proteins • Exalbuminous seeds o Seeds with no endosperm at maturity e.g. sunflower • Albuminous seeds o Have endosperm at maturity e.g. castor seed STEP 5: Key Points (5 minutes) • Seed is the structure formed by plants from a ripened ovule after fertilization and occurs in many shapes and sizes • Seeds may be formed from orthotropous ovules, campylotropous or anatropous ovules • The seed consists of a seed coat which covers the seed and made up of the testa and tegmen • The internal of a seed consists of the embryo and endosperm • In some seeds the endosperm is absorbed and absent at maturity forming exalbuminous seeds while in albuminous seeds the endoperm persists STEP 6: Evaluation (5 minutes) • What is a micropyle? • What are the functions of a seed coat? References Trease, G. E., Evans, W. C., & Evans, D. (2009). Trease and Evans pharmacognosy. London: Saunders. Joanne Barnes et al (2002), Herbal medicines 3rd Edition: Pharmaceutical Press Wallis, T. E. (2005). Textbook of pharmacognosy. New Delhi: CBS. Robbers, J. E., Speedie, M. K., Tyler, V. E., & Tyler, V. E. (1996). Pharmacognosy and pharmacobiotechnology. Baltimore: Williams & Wilkins. Heinrich, M., Kinghorn, A. D., Maizels, D., Gibbons, S., & Phillipson, J. D. (2012). Fundamentals of pharmacognosy and phytotherapy. Edinburgh: Churchill Livingstone/Elsevier. ← Previous TopicNext Topic →View all Basic Pharmacognosy topicsOpen Complete Full Notes PDF / OFFLINE NOTES Unataka kutumiwa notes hizi kupitia WhatsApp?Kwa notes zilizopangiliwa vizuri kwa kusoma offline au PDF, bonyeza kitufe hapa chini. Ujumbe wenye Level, Semester, Module na Topic utaandaliwa moja kwa moja.TUMIWA NOTES WHATSAPP WhatsApp: 255620339260

NTA Level 5 • Semester 2 • PST05210 Morphology of the Fruit Basic Pharmacognosy • Source Session/Topic 9 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 9: Morphology of the Fruit Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define a fruit • List parts of a fruit • Classify fruits Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |25 minutes |Presentation |Introduction to Fruits | | | |Buzzing | | |3 |30 minutes |Brainstorming |Structure of the Fruits | | | |Presentation | | |4 |50 minutes |Presentation |Classification of Fruits | |5 |05 minutes |Presentation |Key Points | |6 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Introduction to Fruits (25 minutes) |Activity: Buzzing (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What is a fruit? | | | |ALLOW few students to respond? | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARISE by using the content below | • Fruit is the ripened ovary or ovaries of a seed-bearing plant • Fruits may contain one or more seeds • A fruit develops from one or more carpels • After fertilization in the flowering stage, the ovary and sometimes accessory parts develop into the fruit • In some species, fruits may be formed without fertilization i.e. parthenocapy • Accessory parts including sepals, petals, stamens, receptacle, pedicel, peduncle and inflorescence axis may be incorporated and become part of the fruit for instance in apples and pineapple STEP 3: Structure of the Fruit (30 minutes) |Activity: Brainstorming (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What are the parts of the fruit? | | | |ALLOW few students to respond? | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARIZE by using the content below | • Fruits consist of dermal, ground (fundamental), and vascular tissue systems • The fruit wall is made up three layers collectively forming the pericarp; o Exocarp ▪ The outermost layer o Mesocarp ▪ The middle layer o Endocarp ▪ The inner layer • The fruits may also contain one or more seeds STEP 4: Classification of Fruits (45 minutes) • Fruits that are formed without including the accessory structures are called true fruits e.g. tomatoes while those including accessory structures are false fruits e.g. pears. • Fruits may be classified based on the number of ovaries, number of flowers and other structures forming the fruit, into; o Simple fruits ▪ Fruits formed from one ovary in one flower o Aggregate fruits ▪ Fruits formed from more than one ovary of one flower o Multiple fruits ▪ Fruits formed from an inflorescence and include accessory structures • After maturity, fruits are also classified into fleshy/Succulent or dry fruits o Fleshy/Succulent fruits may be soft or hard ▪ Simple succulent fruits • Have soft and fleshy epicarp and formed from single ovary • They include; o Berries ▪ Have soft epicarp and fleshy mesocarp and endocarp o Hesperidiums ▪ Berries with a thicker skin containing oils o Pepos ▪ Berries with a comparatively thick exocarp or rind o Drupes/stones ▪ Have edible exocarp and fleshy mesocarp and inedible, hard stone-like endocarp o Pome ▪ A fleshy fruit with mature ovary and accessory structures e.g. petals, sepals and receptacle o Polydrupes ▪ Are soft aggregate fruits (fusion of several drupes) e.g. strawberries, blackberries etc. o Dry fruits may be dehiscent or indehiscent depending on whether they split open to release the seeds or not. They include; ▪ Simple dry indehiscent fruits • Samara o A winged fruit • Achene o A hard dry fruit with one seed which almost feels the pericarp but attached loosely • Nuts o Simple dry fruit similar to achenes, but formed from two or three carpels. Pericarp is relatively hard and heavy • Caryopsis o It is a simple, dry fruit in which the testa and pericarp are fused ▪ Simple dry dehiscent fruits • Legumes o Are dry fruits which split along both dorsal and ventral sutures to release their seeds e.g. Cassia angustifolia • Follicles o Dry fruits which splits along inner suture only e.g. strophanthus • Capsules o Dry fruits formed from two or more carpels ▪ Valvate Capsule –the tip split open ▪ Porose capsule –form pores to release seeds ▪ Loculicidal capsules –splits along locules ▪ Circumscissile capsules –split through the centre of the fruit ▪ Septicidal capsule –split along the septa STEP 7: Key Points (5 minutes) • Fruit is the ripened ovary or ovaries of a seed-bearing plant containing one or more seeds • Fruits that are formed without including the accessory structures are called true fruits • A fruit is composed of the fruit wall and seeds • The fruit wall is made up three layers, exocarp, mesocarp and endocarp which collectively form the pericarp • Fruits are classified based on the number of ovaries, number of flowers and other structures forming the fruit • After maturity, fruits are also classified into fleshy or succulent fruits and dry fruits STEP 8: Evaluation (5 minutes) • What is a fruit? • What are dry fruits? References Trease, G. E., Evans, W. C., & Evans, D. (2009). Trease and Evans pharmacognosy. London: Saunders. Joanne Barnes et al (2002), Herbal medicines 3rd Edition: Pharmaceutical Press Wallis, T. E.

NTA Level 5 • Semester 2 • PST05210 Morphology of the Flower Basic Pharmacognosy • Source Session/Topic 8 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 8: Morphology of the Flower Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define the flower • List parts of flowers • Classify flowers Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD projector and Laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |20 minutes |Buzzing |Introduction to Flowers | | | |Presentation | | |3 |40 minutes |Presentation |Structure of the Flower | |4 |45 minutes |Presentation |Classification of Flowers | |5 |05 minutes |Presentation |Key Points | |6 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Introduction to Flowers (20 minutes) |Activity: Buzzing (5 minutes) | | | |ASK students to pair up and buzz on the following question for 2 | |minutes | | | |What is a flower? | | | |ALLOW few pairs to respond and let other pairs to add on points not| |mentioned | | | |WRITE their response on the flip chart/board | | | |CLARIFY and SUMMARIZE by using the content below | • Flower is the plant organ for sexual reproduction • The flower produces gametes (sex cells) • Flowers are produced on the stem of the plant • Floral parts in monocotyledonous plants are divided into three or multiple of three • Floral parts in dicotyledonous plants occur in four or five • Flowers may be unisexual or bisexual o Dioecious plants ▪ Are plants with unisexual flowers appearing on different plants o Monoecious plants ▪ Unisexual male and female flowers appear on the same plant o Polygamous plants ▪ Plants that bear unisexual and hermaphrodite flowers on the same plant • Functions of the flower to the plant include; o Flowers help in pollination process by insects, wind, birds, mammals or by water ▪ Flowers pollinated by insects have bright colours, sweet fragrance and produce nectar ▪ Flowers pollinated by wind have large stigmas, no or little fragrance, and non- sticky pollens ▪ Flowers pollinated by birds are log tube shaped, have bright red or yellow colours, and with no fragrance ▪ Flowers pollinated by mammals have white flowers with strong fruity smell and open at night ▪ Flowers pollinated by water may have pollens which floats on water STEP 3: Structure of the Flower (40 minutes) • A typical flower is made up of the following parts; o Peduncle –the flower stalk o Receptacle –bears the floral organs ▪ Forms the hypanthium if elongated below the calyx ▪ If below the ovary it is the gynophore or stalk of the ovary o Calyx –made up of sepals (to protect young flower bud) ▪ Polysepalous if sepals are separate ▪ Gamosepalous if sepals are fused o Corolla –made up of petals (often colourful) ▪ Polypetalous if petals are separate ▪ Gamopetalous if petals are fused o Perianth –formed from sepals and petals together o Stamen –male reproductive structures of the flower ▪ Made up of anther and filaments (produce pollen grains) ▪ Monadelphous if stamens are fused ▪ Diadelphous if stamens are separate o Pollen -Grains containing the male gametes o Pistil –female part of the flower ▪ Made up of stigma, style and ovary o Carpel –A unit of compound pistil or ovary o Ovule –bears the female gametes, located in the ovaries o Gynoecium –one or more pistils (carpel, ovary, ovules, female gametes) o Androecium –one or two whorls of stamens (filament, anther, pollen grains, male gametes) STEP 4: Classification of Flowers (45 minutes) • Flowers are classified in various groups based on different criteria o Based on presence of male, or female or both reproductive structures ▪ Perfect/Bisexual/Hermaphrodite Flower • These flowers bear both male and female reproductive structures ▪ Imperfect/Unisexual Flower • Bears male or female reproductive structures • Staminate flower (male flower) • Pistillate/carpellate flower (female flower) o Based on presence or absence of any structure ▪ Complete Flower • Flowers bear sepals, petals, pistils, and stamens ▪ Incomplete Flowers • Sepals, petals, pistils, or stamen is missing o Based on the number of flowers ▪ Simple flowers • One flower on an axis (receptacle) o Compound flowers or Inflorescence • Have more than one flower on the receptacle or axis • The axis forms the rachis and florets are attached on pedicels o Inflorescence are subsequently classified based on pattern of arrangement into; • Single inflorescence –same pattern of arrangement of florets • Compound inflorescence –complex pattern • Main inflorescences include; o Raceme (or racemose) o Spadix o Spike o Corymb o Umbel o Head o Based on flora variations ▪ Flowers are grouped according to the placement of floral parts on the receptacle into; • Hypogynous flowers o Sepals, petals, and stamens are attached to a convex or conical receptacle at the base of the ovary o The ovary is called superior and the perianth is inferior or hypogynous • Perigynous flowers o Sepals, petals, and sometimes stamens borne on the edge or margin of the receptacle and appear to form a cup around the pistil • Epigynous flowers o Sepals, petals, and stamens appear to arise from the top of the ovary o The ovary is inferior and the perianth is superior or epigynous o Based on floral symmetry ▪ Regular or Actinomorphic flowers • Flowers divisible into symmetrical halves by more than one longitudinal plane through the axis ▪ Irregular or

NTA Level 5 • Semester 2 • PST05210 Morphology of the Leaf Basic Pharmacognosy • Source Session/Topic 7 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 7: Morphology of the Leaf Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define a leaf • List external structures of a leaf • List internal structures of a leaf • Explain the anatomy of a leaf • Explain the criteria used in classification of leaves • Explain the pharmacognostic importance of leaves Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD projector and Laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |5 minutes |Presentation |Introduction, Learning Tasks | |2 |15 minutes |Buzzing |Introduction to Plant Leaves | | | |Presentation | | |3 |40 minutes |Presentation |Internal Structures of the Plant | | | |Brainstorming |Leaf | |4 |25 minutes |Presentation |Pharmacognostic Importance of | | | | |Epidermis | |5 |25 minutes |Presentation |Classification of Leaves | |6 |5 minutes |Presentation |Key Points | | 7|5 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Introduction to Plant Leaves (15 minutes) |Activity: Buzzing (5 minutes) | | | |ASK students to pair up and buzz on the following question for 2 | |minutes | | | |What is a leaf? | | | |ALLOW few pairs to respond and let other pairs to add on points not| |mentioned | | | |WRITE their response on the flip chart/board | | | |CLARIFY and SUMMARIZE by using the content below | • A leaf is a plant organ that is found above the ground and is specialized for photosynthesis • The leaf is typically flat and thin • Functions of the leaf o Provides for transpiration and guttation o Storage of food and water • The leaf consists of a petiole, a lamina (or the leaf blade), and stipules o Petiole ▪ Attaches the leaf to the stem ▪ Some leaves are directly attached to the stem without a petiole o The lamina ▪ Is flat and offers surface for trapping sunlight for photosynthesis STEP 3: Internal Structures of a Plant Leaf (40 minutes) |Activity: Brainstorming (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What are the internal structures of the plant leaf? | | | |ALLOW few students to respond? | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARIZE by using the content below | • The leaf is made up of three tissue systems (Dermal, Ground and Vascular) • The dermal tissue system consists of lower and upper epidermis • The ground tissue system is found between the epidermal layers of leaf o Epidermis ▪ In dicot leaves, the epidermis is dorsiventral ▪ Generally, the epidermis is made up of a single layer of cells that are closely packed and covered with a cuticle ▪ The epidermal tissue is made up of; • Epidermal cells • Guard cells • Subsidiary cells • Epidermal trichomes o Epidermal cells ▪ Epidermal cells are the most numerous, largest, and least specialized ▪ Epidermal cells are more elongated in the leaves of monocots than in dicots o Guard cells ▪ Consist of a pair of bean- shaped cells surrounding the stoma ▪ They contain chloroplasts ▪ Other epidermal cells do not contain chloroplasts o Subsidiary cells ▪ They are 2 to 4 cells that surround the stoma ▪ They do not contain chloroplasts o The epidermal layer consists of stomata ▪ The stomata are part of a stoma complex which consists of a pore surrounded on each side by guard cells and subsidiary cells ▪ The stoma complex regulates the exchange of gases and water vapour between the outside air and the interior of the leaf ▪ There are more stomata over the abaxial that the adaxial epidermis. • Main function of the epidermis is to protect inner tissues Figure 7.1: Transverse Section of a Leaf [pic] • Mesophyll o Mesophyll is the entire tissue between the upper and lower epidermis is Mesophyll is differentiated in two regions; ▪ Palisade parenchyma and ▪ Spongy parenchyma • This differentiation gives two anatomical designations of the leaf • Dorsiventral leaf • Mesophyll is differentiated into palisade parenchyma (or palisade mesophyll) on the adaxial (upper) side and spongy parenchyma (or spongy mesophyll) on the abaxial (lower) side • Common in dicot leaves • Isobilateral leaf • Leaf mesophyll is not differentiated this way (i.e., made of only spongy or palisade parenchyma) • Common in monocots o Palisade Parenchyma (Palisade Mesophyll) ▪ Palisade parenchyma lies beneath the adaxial epidermis ▪ Palisade mesophyll may be present below both surfaces or occur only below the upper epidermis ▪ Consists of vertically elongated cylindrical cells in one or more layers ▪ Cells are compactly arranged with the chloroplasts close to the walls of the cell ▪ Main function is photosynthesis o Spongy Mesophyll ▪ Lies below the palisade mesophyll, with irregularly shaped, loosely arranged cells ▪ Contain fewer chloroplasts than palisade mesophyll ▪ Spongy cells facilitate exchange of gases with the help of air spaces ▪ The pores or stomata of the epidermis open into sub stomatal chambers, connecting to air spaces between the spongy layer cells o Vascular Tissues ▪ Veins are the vascular tissue of the leaf located in the spongy layer of the mesophyll ▪ Based on pattern of venation, the vascular system of leaves falls into two main classes: • The reticulate (or net) venation typical of dicotyledons • The

NTA Level 5 • Semester 2 • PST05210 Morphology of Stems Basic Pharmacognosy • Source Session/Topic 6 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 6: Morphology of Stems Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Introduction of the Stem • External Structure of the Stem • Differentiate Dicot from Monocot Stem • Functions of the Stem Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD projector and laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |20 minutes |Presentation |Introduction to Stems and External| | | |Brainstorming |Features | |3 |35 minutes |Presentation |Internal Structures of Dicot Stems| |4 |30 minutes |Presentation |Internal Structures of Monocot | | | | |Stems | |5 |20 minutes |Presentation |Differences between Monocot and | | | |Small group |Dicot Stems | | | |discussion | | |6 |05 minutes |Presentation |Key Points | |7 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Introduction to Stems and External Features (20 minutes) • Stem is the axis of the plant other than the root • In most plants stems are located above the soil surface but some plants have underground stems • Functions of the stem o Stems support the leaves and other structures e.g. flowers, fruits o Stems are used for vegetative reproductive i.e. cuttings o Stems position leaves to receive maximum sunlight o Stems determine size and shape of the plant o Facilitates movement of water, minerals, and manufactured food in the plant o Some stems carry out photosynthesis o Stores foods |Activity: Brainstorming (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What are the external structures of the stem? | | | |ALLOW few students to respond? | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARISE by using the content below | • External structures of the stem o Internodes: distances separating one node from another o Nodes: Points at which leaves are attached o Lenticels: Breathing pores o Buds: Growth of shoot o Terminal or apical but, at tip of plan o Axillary bud in nodes on stem o Bud scale scars: Indicate where terminal bud has been located previous year o Leaf scars: o Show where leaf was attached • Internal structures of the stem o Usually consist of three tissues, Dermal tissue, Ground tissue and Vascular tissue o The dermal tissue ▪ Covers outer surface of stem and usually functions to waterproof, protect & control gas exchange o The Ground tissue ▪ Mainly of parenchyma cells and fills in around the vascular tissue, sometimes functions in photosynthesis o The Vascular tissue ▪ Provides long distance transport and structural support ▪ Arrangement varies widely among plant species STEP 3: Internal Structures of the Dicot Stem (35 minutes) • Internal structure of dicotyledonous stem consists of Epidermis, Cortex and Stele. o Epidermis ▪ It consists of a single layer of parenchymatous rectangular cells ▪ Epidermal cells are compactly arranged without intercellular spaces ▪ Epidermis is covered on the outside by cuticle made up of waxy substance ▪ The cuticle checks/controls transpiration ▪ Stomata may be present at irregular intervals ▪ A large number of multicellular hairs occur on the epidermis o Cortex ▪ Cortex lies below the epidermis ▪ The cortex is differentiated into three zones ▪ The first zone (Hypodermis) • Lies below the epidermis, consists of a few layers of collenchyma cells ▪ The second zone • Lies inner to the hypodermis • Consists of a few layers of chlorenchyma cells • Some resin ducts also occur in this zone ▪ The third zone • Consists of parenchyma cells • The innermost layer of the cortex is the endodermis • Made of barrel shaped cells arranged compactly without intercellular spaces • Rich in starch grains, hence “starch sheath” • In most dicot stems no casparian strips [pic] o The Stele ▪ In the central part of the stem inner to the endodermis ▪ It consists of pericycle, vascular bundles and pith ▪ Vascular bundles are arranged in a ring around the pith • Pericycle o Layers of cells between endodermis and vascular bundles • Vascular Bundles o Consist of xylem, phloem and cambium o Xylem and phloem in stem occur together to form the vascular bundles o These vascular bundles are wedge shaped o The vascular bundle is conjoint, collateral, open and endarch o Phloem • Consists of sieve tubes, companion cells and phloem parenchyma • Phloem conducts organic food materials from the leaves to other parts of the plant body o Cambium • Consists of brick shaped and thin walled meristematic cells • Form new cells during secondary growth o Xylem • Consists of xylem fibres, xylem parenchyma, vessels and tracheids • Vessels are thick walled and arranged in a few rows • Conducts water and minerals from the root to the other parts of the plant body • Pith (medulla) o It is the large central portion of the stem o It is composed of parenchyma cells with intercellular spaces o The pith extends between the vascular bundles and form primary medullary rays o These extensions of the pith between the vascular bundles are called o It stores food STEP 4: Internal Structures of the Monocot Stem (30 minutes) • Internal structure of monocotyledonous stem consists of: o Epidermis, o Hypodermis, o Ground tissue and o Vascular bundles ▪ Epidermis • It is the outermost layer of the

NTA Level 5 • Semester 2 • PST05210 Morphology of the Roots Basic Pharmacognosy • Source Session/Topic 5 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 5: Morphology of the Roots Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Explain Roots • Classify Roots • Differentiate Monocotyledon from Dicotyledon • Functions of the Roots Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |25 minutes |Presentation |Characteristics of Plant | | | | |Roots | |3 |30 minutes |Presentation |Anatomy of Monocotyledonous | | | | |Roots | |4 |30 minutes |Presentation |Anatomy of Dicotyledonous | | | | |Roots | |5 |20 minutes |Presentation |Difference between Monocot | | | |Small group |and Dicot Roots | | | |Discussion | | |6 |05 minutes |Presentation |Key Points | |7 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing STEP 2: Characteristics of Plant Roots (25 minutes) • The root constitutes the underground part of the plant axis. • It is an organ of the plant that typically lies below the surface of the soil • Externally the root has root hairs which aid in absorption of water minerals • Roots can be classified in three main categories: o Tap roots ▪ One large vertical root ▪ Also produces many small lateral or branch roots ▪ These are common in dicotyledonous plants o Fibrous roots ▪ Mat of thin roots that spread out ▪ Made up of many thread-like members of more or less equal length ▪ These are common in monocotyledonous plants o Adventitious roots ▪ Form on any plant part other than the roots ▪ They commonly occur in grasses • General Internal structure of the root; [pic] • Functions of the Roots o The following are the functions of the roots ▪ Roots support (anchorage) the plant in the soil (or other media in which the plant is growing) ▪ Absorption of water and other nutrients from the soil ▪ Storage of food ▪ Transport minerals and water to other parts of the plant STEP 3: Anatomy of the Monocotyledonous Roots (30 minutes) • Internal structure of monocot roots shows the following tissue systems o Epiblema or rhizodermis o Cortex and o Stele Fig 5.1: Internal Structure of the Monocotyledonous Root [pic] • The Rhizodermis or Epiblema o Outermost layer of the root o Single row of parenchyma cells, no intercellular space o Stomata and cuticle are absent o Root hairs are always unicellular o The key function of rhizodermis is protection of the inner tissues of the root • The Cortex o The cortex is made of only one type of tissue (parenchyma) o Has many layers of parenchyma cells with lot of intercellular spaces o Cortical cells are generally oval or rounded in shape; chloroplasts are absent o The cells are living and possess leucoplasts o The inner most layer of the cortex is endodermis and is composed of single layer of barrel shaped parenchymatous cells o The function of cortical cells is storage o Endodermis (innermost layer of cortex) forms a complete ring around the stele (tissues inside endodermis) o There is a band-like structure made of (thickened with) suberin present in the radial and transverse walls of the endodermal cells o The band is called Casparian strips o The endodermal cells opposite to the protoxylem elements, are thin- walled without Casparian strips o These cells are called passage cells and their function is to transport water and dissolved salts from the cortex to the xylem o Water cannot pass through other endodermal cells due to Casparian strips (blocking effect) o The main function of Casparian strips in the endodermal cells is to prevent the re-entry of water into the cortex once water enters the xylem tissue • Vascular System (Stele) o Vascular tissues are in radial arrangement with many protoxylem groups o This arrangement of xylem is called polyarch and the xylem is in exarch condition o The tissue present between the xylem and the phloem, is called conjunctive tissue • The Pith o The central portion o It consists of thin walled parenchyma cells with intercellular spaces o These cells are filled with abundant starch grains STEP 4: Anatomy of the Dicotyledonous Roots (30 minutes) • The Dicotyledonous Root o Structure of a Dicotyledonous Root [pic] • Rhizodermis or Epiblema o Outermost layer aka rhizodermis (epidermis in stems) made of a single layer of parenchyma cells which are arranged compactly without intercellular spaces, with no stomata or cuticle o Root hair is always single celled o Protects inner tissues of the root • The Cortex o Consists of only parenchyma cells loosely arranged with intercellular spaces to make gaseous exchange easier o These cells may store food reserves o The cells are oval or rounded in shape o Sometimes are polygonal due to mutual pressure o Cortical cells are devoid of chloroplasts but starch grains are stored in them o The cortical cells also possess leucoplasts o Inner most layer of the cortex is endodermis o Endodermis is made up of single layer of barrel shaped parenchymatous cells o Stele is completely surrounded by the endodermis o The radial and the inner tangential walls of endodermal cells are thickened with suberin o Casparian strips o Casparian strips are absent in the endodermal cells located opposite to the protoxylem elements o These thin-walled cells without Casparian strips are called passage cells through which water and mineral salts are conducted