Transcript ANATOMI
ANATOMY Refers to the internal structure of plants. The plant body is made up of groups of identical as well as complex cells. Anatomical Characteristics Assist Us in Understanding: 1. The process of photosynthesis, absorption and movement of water, as well as the translocation of food. 2. The success and failures of horticultural practices such as pruning, grafting and other forms of vegetative propagation. 3. Plant Pathology, particularly the anatomical structure of plant parts that are attacked thus giving further insight on the parasitic effect. 4. Taxonomy. Main Topics A. Types of Cells and Tissues B. Primary and Secondary Growth : root, stem, leaf, flower, fruit and seed TISSUES Meristematic Tissues - apical meristem - lateral meristems - intercalary meristem Tissue: A group of cells that perform similar function(s) Non Meristematic Tissues Simple tissues - parenchyma - collenchyma - sclerenchyma Complex tissues - xylem - phloem - epidermis - periderm - secretory cells and tissues Meristematic tissue - - Consists of newly formed cells, small sized, with thin cell wall and dense protoplasm, box shaped and having six surfaces, a large nucleus and small vacuoles Cells are always actively dividing When mature, the cell shape differs according to the cell function, while the vacuoles increase in size Meristematic cells Apical meristem - found at the tip of shoots and roots - The plant lengthens as the apical meristem produces new cells ** Gives rise to 3 primary meristems: protoderm, ground meristem, and procambium (which forms the xylem dan phloem). Primary meristem produces the primary tissues primary growth Shoot apical meristem Primary meristems in a shoot apex Root apical meristem Lateral meristems - Vascular cambium and cork cambium - Produce tissues that increase the girth of stem and roots - Vascular cambium : a thin cylinder in stem and root of annuals and perennials - Cork cambium : a thin cylinder in stem and root of woody plants, found outside the vascular cambium and within the bark of plants - Tissues produced from both the vascular cambium and cork cambium are secondary tissues formed after the maturation of the primary tissues secondary growth Lateral meristem Intercalary meristem - Grass species (Graminae) do not possess vascular cambium and cork cambium, instead they have apical meristem and intercalary meristem - Intercalary meristems are found close to the node region, producing primary tissues that result in the increase in length (elongation) of stems. Intercalary meristem NON-MERISTEMATIC (SIMPLE TISSUE) 1. Parenchyma tissue consists of parenchyma cells, the most abundant tissue in the plant body, found almost in all important parts of flowering plants. Parenchyma cells: Living cells, almost round in shape when first formed The cell surface becomes even and smooth when the thin cell wall touches each other Can form diverse shapes and sizes, mostly having 14 surfaces Contains a large vacuole and perhaps starch, oil, tannin, crystals and various forms of secretion Perform the basic metabolic functions of cells: respiration, photosynthesis, storage and secretion Having intercellular spaces *parenchyma cells with large intercellular spaces are termed arenchymas *parenchyma cells that contain abundant chloroplasts are termed chlorenchymas *Transfer cells - parenchyma cells with elongated plasmalema, large cell surface, facilitate short distance transport between cells Parenchyma cells Parenchyma Elodea leaf showing chlorenchymas ARENCHYMA 2. Collenchyma tissue - consists of living cells, the shape is more elongated than broad - with rather thick cell wall - the cell wall is very flexible but strong – functions to give support to stem, leaves and flower parts - collenchyma cells originate from parenchyma cells - found below the epidermis, close to the leaf midribs and veins, or near vascular bundles Collenchyma tissue Stem cross section of Sambucus spp. Collenchyma in leaf midrib 3. Sclerenchyma tissue - cells possess a thick and strong secondary wall composed mainly of lignin (a polymer) - cells are dead (lacking a living protoplast) when mature - function to provide support and sometimes protection to the plant - There are two forms of sclerenchyma cells: sclereid and fibre fibre Sclerenchyma Sclereids - originate from parenchyma cells - cell shape : width equal length (isodiametric) - spread randomly within the plant tissue and exists in various forms or shapes: brachysclereid osteosclereid trichosclerid macrosclereid astrosclereid - a gritty texture that occurs in pears is due to the presence of sclereids - sclereids are sometimes Sclereids in pear found in leaves and in seed coat (particularly the testa) Sclereids in bean seed coat Various forms of sclereids a. Brachysclereid (sel batu) d. Astrosclereid b. Macrosclereid e. Trichosclereid c. Osteosclereid Sclereids Sclerieds (stone cells) in fruit tissue of pear Sclerieds in cross section of a water lily leaf Fibres - often found among other tissues of plant organs - the shape is more elongated than wide - the cavity in the middle of the cell is termed lumen - economic importance of fibres : for making ropes, canvas etc.