Lecture 3 (Medicinal Plants) 2024/2025

Medicinal plants 2024/2025 Lecture 3 Dr. Amal F. Soliman Dr. Walaa Safwat Associate Professor of Pharmacognosy Lecturer of Pharmacognosy A B D C Write the description or the name of the following trichome...

Medicinal plants 2024/2025 Lecture 3 Dr. Amal F. Soliman Dr. Walaa Safwat Associate Professor of Pharmacognosy Lecturer of Pharmacognosy A B D C Write the description or the name of the following trichomes:  Plant tissues Apical Meristematic Intercalary Vascular cambium Cork Types of Lateral cambium Tissue Dermal Interfascicular cambium permanent Ground Vascular Secretory ‫‪B) The ground or fundamental tissue‬‬ ‫اخلالاي الكولنش ميية‬ ‫اخلالاي الربنش ميية‬ ‫اخلالاي الاسلكرنش ميية‬ ▪ They are living cells, having large ▪ They are living cells, more elongated vacuoles and thin wall consists of and narrower than parenchyma cells cellulose. with non-lignified thick walls (Cellulose, hemicellulose and ▪ Parenchyma cells perform pectin). several functions as storage of water and food such as starch, fat ▪ They act as a supporting tissue in and protein. young growing organs as stems and leaves.  Parenchyma Chlorenchyma ▪ If chloroplasts are present, these cells can carry photosynthesis and usually known as chlorenchyma. Aerenchyma cells ▪ Modified parenchyma consisting of chains of small cells enclosing very wide intercellular spaces. ▪ Parenchyma tissue with extensive connected air spaces. ▪ Aerenchyma is widespread in aquatic plants (help in floating of plant). Sclerenchyma ▪ They are non-living cells with thick often lignified secondary wall. ▪ Made up of a primary wall (cellulose) and a secondary wall (lignin). ▪ They are classified into a) Fibers b) Sclereids ▪ Function of Sclerenchyma: support Sclerides are usually isodiametric to rectangular or elongated cells, but not much longer than they are broad. Fibers are elongate sclerenchyma cells with usually pointed ends. C) The vascular or conducting tissue ▪ They are composed of Xylem, the principal water conducting tissue and Phloem, the food conducting tissues. ‫اخلشب‬ ‫اللحاء‬ Xylem ‫اخلشب‬ Xylem is a complex tissue; it consists of several types of cells. The characteristic components are the tracheary and atracheary elements. The tracheary elements (tracheids and vessels) combine the function of conduction with that of support. Atracheary elements, Xylem fibers and parenchyma. They have no role in conduction, they are specialized supporting elements.  Conduction and support Tracheids Tracheary elements Vessels Xylem elements Xylem Atracheary fibers elements Xylem Support only parenchyma  The tracheary elements (tracheids and vessels) combine the function of conduction with that of support. ▪ Each tracheid is a single, ▪ Vessels are narrow or elongated cell with bluntly wide water conducting tapering tubes, formed from..ends (Non- number of cells, by a perforated end walls)... partial or complete ▪ Pitted (bordered type pits). disintegration of their end walls (perforated end walls). ‫القصبات الهوائية‬ Tracheids Vessels ‫ا ألوعية‬ Types of xylem vessels: 1- Annular When the thickening are in the form or rings at intervals. 2- Spiral when the wall show a spiral line of thickening. 3- Reticulate When the thickening of the walls takes the form of network. 4- Pitted or bordered pitted When the whole wall becomes thickened except of numerous small areas or pits which are usually bordered. 5- Scalariform Pits are transversely elongated giving a ladder- like appearance.  Tracheids Vessels Phloem ‫اللحاء‬ Phloem is a complex tissue, composed of several different kinds of cells. The main phloem elements are the sieve elements which are the principal food conducting tissue of the vascular plants. They are composed of: o Sieve tubes o Companion cells o Phloem parenchyma o Phloem fiber  Types of V.B. ‫احلزم الوعائية‬ The phloem and xylem are associated with each other within V.B., the variation in the arrangement of these vascular tissues in the bundles have led to the establishment of different bundle types. 1- Collateral: phloem outside and xylem inside (on the same radius). a- Open: In most dicot. stems. It has a vascular cambium between Xylem and phloem. b- Closed: In monocot. plants. The vascular bundles have no cambium. 2- Bicollateral: Xylem occur between two patches of phloem on the same radius. Such bundles occur in dicot stem. 3- Concentric: (One kind of vascular tissue surround one another). a- Amphicribral: if phloem surrounds the xylem. b- Amphivasal: if xylem surrounds the phloem. 4- Radial: xylem and phloem patches are on different radii alternating with each other (as in root). Each phloem strand is separated from adjacent xylem by parenchyma cells. Amphicribral Amphivasal Radial  Closed collateral V.B. Skull shaped (Monocot) D) The secretory tissue Glandular Cells hairs Glands Hydathodes Ducts Nectaries Glands classified into: Have central cavities in the tissue. These cavities originate in two ways: ✓ Schizogenous Through the dissolution of the middle lamella. It is characterized by the regular cavity and by the presence of special layer of small cells round the internal cavity. ✓ Lysigenous through the dissolution of entire cells, leaving a space in which the secretion accumulates and the cavities usually contains the remains of cells. 2- Digestive glands: ‫الغدد الهامضة‬ Certain plants possess a highly characteristic method of nutrition known as the insectivorous or carnivorous habit. The function of these glands: 1- Pour out a sticky secretion to aid in insect capture. 2- Or to supply protein-digesting enzymes, these enzymes act upon the captured organisms so that the products of digestion can be absorbed by plant. 3- Nectaries ‫اخلالاي الرحيقية‬ o These are simply modified epidermis found in most flowers (rare in leaf or stem where they are called extra-floral). o The epidermis of these gland areas has no cuticle. o They secrete sugary substance, known as nectar, it serves to attract insects. 4- Hydathodes (water stomata) It associated with water excretion. o It is a permanently open stomata supplied beneath with a strand of vascular cells. o On warm damp nights, when abundant absorption occurs and the stomata are closed, the excess moisture is removed through these glands. o Hydathodes often occur at leaf margins. 5- Ducts ‫القنوات‬ Resins, latex, gums are often secreted and conducted within the plant body in ducts. ▪ Laticiferous ducts release their milky secretions out when they are cut open. Some lateces have great economic importance especially the hydrocarbon substance called caoutchouc, the source of rubber. Other lateces are of medical interest like that of papaver, source of opium.  Apical Vascular Meristematic Intercalary cambium Cork Lateral cambium Types of Tissues Interfascicular Dermal cambium Vascular Permenant Ground Secretory Give only the term corresponding to the following sentences: - A vascular bundle with phloem on two sides of the xylem on the same radius. Modified epidermal cells which has no cuticle, secrete sugary substances to attract insects. Supporting xylem element consists of single elongated cell and has non-perforated end walls. A permanently open stomata at the leaf margin through which excess water excreted. * Match the following statements (write only the numbers next to the matched sentence). Item Sentence 1 Diacytic stomata Widely spread in aquatic plants. 2 Sclerenchyma Vascular bundles in monocot plants. 3 Skull shaped One of the subsidiary cells is distinctly smaller. 4 Aerenchyma Non-living tissues. 5 Anisocytic stomata Guard cells of stomata in dicot plants. 6 Kidney shaped Axis of the two subsidiary cells is perpendicular to the osteole. Complete the following sentences: - 1- The structure in which protein stored is called……………. 2- The type of xylem vessels when the thickening showed ladder like appearance is called ………………………. 3- Meristematic tissue lies at the internodes of monocot plants is known as …………………………………. 4- The type of vascular bundles in which xylem surrounds the phloem is ……………………………….. 5- Striation with eccentric hilum can be seen in ……………..starch. * Mention the name, tissue and the function. A B Give only the term corresponding to the following sentences: - A type of modified parenchyma tissue with large air lacunae (spaces). Outermost structure of plant cells surrounding the protoplast. A modified type of parenchyma cells with an abundance of chloroplasts. Needle-like crystals of calcium oxalate; often occur in groups.