Plant Tissues Lecture 1 PDF

PLANT STRUCTURE: PLANT (Angiosperm) TISSUES BIOL0012 Lecture 1  Assessable Objective At the end of this topic you should be able to : Classify various plant tissues Identify the cells belonging to plant tissues Describe plant tissues & their location in the organ State th...

PLANT STRUCTURE: PLANT (Angiosperm) TISSUES BIOL0012 Lecture 1  Assessable Objective At the end of this topic you should be able to : Classify various plant tissues Identify the cells belonging to plant tissues Describe plant tissues & their location in the organ State the function of the various tissues  Plant Tissues The body of organisms in the Kingdom Plantae are composed of eukaryotic cells. Plants are multicellular and have tissue differentiation; the cells are organized into specialized tissues Tissue: group of cells that perform similar function The various tissues are distributed in characteristic patterns and interconnected throughout the plant body.  Plant Tissues Development of an organism involves: Growth Morphogenesis Differentiation irreversible increase in acquisition of a cells of identical genetic makeup becoming size by cell division and particular shape different from one another and different from cell enlargement the cells from which they originated In plants (and animals) continuous groups of differentiated and specialized tissues connect various sections. (roots, stems, leaves and maybe flowers). This is necessary for normal growth and development which depends on the distribution of air, food and other necessary materials throughout the body.  Plant tissue classification: by complexity Simple tissues Complex tissues comprised of one type of cell comprised of more than one e.g. parenchyma, collenchyma type of cell and sclerenchyma e.g. epidermis, xylem, phloem  Plant tissue classification: by function 1. MERISTEMATIC TISSUE undifferentiated tissue (not yet specialized) which is capable of dividing indefinitely and which produce new growth. 2. DERMAL TISSUE covering/protective tissue represented by the epidermis (primary tissue) and the periderm (secondary tissue).  Plant tissue classification: by function cont’d 3. VASCULAR TISSUE conducting tissues that move water/minerals (xylem) and manufactured products (phloem) throughout the plant. 4. GROUND TISSUE includes all packing, storage and strengthening tissues like collenchyma, parenchyma, sclerenchyma  Meristematic Tissue Rapidly dividing cells that lead to growth Shoot Apical Meristem Root Apical Meristem  Dermal Tissue: Epithelium Epithelium forms the outer surface lines & protects  Vascular Tissue Xylem Vessels Tracheids Parenchyma Fibers Phloem Sieve tubes Companion cells Parenchyma Fibers  Vascular Tissue: Xylem Xylem Vessels Xylem Tracheids At maturity Dead Dead Function Water conduction Water conduction Shape Elongated tapering Elongated tapering Vessel members in series connected by Tracheids connect in series perforated plates Cell wall Primary & Secondary Primary & Secondary Lignified Lignified Perforated. Pitted (not perforated). Found in Angiosperms Gymnosperms & Pteridophytes (also found in Angiosperms) XYLEM PARENCHYMA almost completely surrounds every vessel metabolic activity and storage of nutrients Vascular Tissue: Xylem Xylem Parenchyma  Vascular Tissue: Phloem Phloem is composed of sieve tubes, companion cells, phloem fibres and phloem parenchyma Phloem Fibres: elongated tapering cells with thickened walls found in stems; to give mechanical strength Phloem Parenchyma: living thin walled cells. form the packing tissue between all the other types of cells. stores compounds such as starch  Vascular Tissue: Phloem Sieve Tubes Structure series of cells (sieve elements) joined end to end. cross walls between successive cells are perforated, forming sieve plates. cell walls are thin nucleus disintegrates and disappears, although the cell contents are living at functional maturity Function transports organic compounds (so lumen is filled with sap)  Vascular Tissue: Phloem Companion Cells Structure specialized parenchyma cells that appear with the sieve tube element. elongated, thin-walled with distinct nucleus in the cytoplasm linked with the sieve tubes by small canals (smaller than pits) filled with cytoplasm regulate the metabolic activities of the sieve tube elements Function moves sugar into the sieve tube member from the mesophyll and move sugar out of the sieve tube member at the sink Vascular Tissue: Phloem  Ground Tissue: Parenchyma Parenchyma Most common Living when mature Primary and secondary wall (lignified, suberized or cutinized) Found in mesophyll, cortex, pith, flesh of fruits; also found in vascular tissues and rays Function For photosynthesis, storage and secretion  Ground Tissue: Collenchyma Collenchyma Living when mature; Typically elongated, cigar shaped Unevenly thickened, non-lignified primary walls are soft and pliable Occur in discrete strands under the epidermis in stems, petioles, etc. Found in young elongating stems (often as a cylinder of tissue). Function For supporting plant parts that are still growing; confers flexibility  Ground Tissue: Sclerenchyma Sclerenchyma Thick secondary wall Generally, lack protoplast (cytoplasm & cell membrane) when mature occur as continuous mass; in groups or as individual cells as fibres - long, slender cells in bundles (e.g. hemp or jute) as sclereids - cells variable in shape occurring singly or in aggregates (eg. ground tissue found in seed coats, peanut shell, grit in naseberry, sweet sop) Function strengthen and support especially of non-growing plant parts.