Leaf Anatomy 2025 PDF

 Cytology is the scientific study of cells; the unit of the living organisms  A plant cell is characterized by the presence of cell wall surrounding plasma membrane which enclose the cytoplasm where cellular organelles are found. The cytoplasm together with the nucleus is called the protopl...

 Cytology is the scientific study of cells; the unit of the living organisms  A plant cell is characterized by the presence of cell wall surrounding plasma membrane which enclose the cytoplasm where cellular organelles are found. The cytoplasm together with the nucleus is called the protoplasm. 1. The nucleus: in the center of most cells It is responsible for storing and transmitting genetic information 2. Mitochondria: are the site of various chemical processes involved in the synthesis of energy molecules called ATP (adenosine triphosphate) 3- Ribosomes are the sites where protein molecules are synthesized from amino acids. 4- The endoplasmic reticulum (ER) is a network of membranes.  Granular endoplasmic reticulum is associated with ribosomes; sometimes referred to as rough ER and is involved in packaging proteins for Golgi apparatus.  The smooth ER lacks ribosomes and is the site of lipid synthesis as well as storing and releasing calcium ions. 5-The Golgi apparatus is a membranous sac that serves to modify and sort proteins to a transport vesicles. 6-Plastids: the chloroplasts which contain chlorophyll that is responsible for photosynthesis. 7- Vacuoles: Plant cells are known for having huge vacuoles. Up to-90%.ofthe volume of a mature cell may be taken up by a single large vacuole or several vacuoles  The main function of the vacuoles is to store useful material and digest waste proteins and organelles The main features that characterize plant cells from other eukaryotic organisms are: 1. Presence of cell wall composed of cellulose, hemicellulose, pectin, lignin 2. (c.F cell wall of fungi made of chitin and cell wall of bacteria made of peptidolignan). 3. Presence of plastids 4. Presence of large vacuole 5. Presence of plasmodesma that connect the protoplast of neighboring cells PLANT ANATOMY Also known as Micromprphology of plants and plant histology, is concerned with the microscopic structure of the tissues, cells and organs of plants. CELL  Cell is the fundamental unit of a living organism, the cell consist of a cell wall which surrounds protoplasmic and non-protoplasmic materials Group of cells with identical form and function is known as tissue Plant tissues are divided into three main groups Dermal tissues Vascular tissues Ground tissues DERMAL TISSUES  occurs on the surface of plants and it is a complex tissue consisting of epidermal cells, stomata and trichomes (hairs).  A-Epidermal cells: 1. Single layer 2. No intercellular spaces 3. Show different shape, size and arrangement ( from plant to another), Cell wall may be straight or wavy walls. 4. Covered with a cuticle (water impermeable substance; cutin) may be smooth, warty, or striated 5. Upper epidermis differs from the lower epidermis B- STOMATA  These are openings in the epidermis.  a stomata is made of pair of similar cells , called guard cells, having a pore in the center called osteole for gaseous exchange They occur in both surfaces or only on lower surface.  the epidermal cells surrounding the stoma are called subsidiary cells,  on the base of arrangement of the subsidiary cells, stomata are divided into four different types Lower epidermis of a leaf Upper epidermis of the same leaf  TYPES ACCORDING TO THE CHARACTERS AND ARRANGEMENT OF SURROUNDING CELLS (SUBSIDIARY CELLS) 1- Ranunculaceous or Anomocytic The surrounding cells (subsidiary cells) are of varying number have no special arrangement and generally do not differ from other epidermal cells e.g. Digitalis. 4- Cruciferous or Anisocytic (unequal celled): the stoma is surrounded by usually three or more subsidiary cells one of which is distinctly smaller than the others e.g. Belladonna. 3- Rubiaceous or Paracytic 4-Caryophyllaceous or (parallel celled): the stoma Diacytic (cross celled): is surrounded by two or the stoma is surrounded more subsidiary cells, two by subsidiary cells having of which have their long their long axes axes parallel to the osteole perpendicular to the e.g. Senna. osteole e.g. Mentha. 3- TRICHOMES (HAIRS) Hairs are projections of Epidermal cells of variable shape and size  If it is short and conical it is called papillae and the epidermis is described as papillosed e.g. Coca, but if the projections are long and well protruding they form trichomes or hairs.  Hairs are classified into glandular and non-glandular or covering hairs.  Non-glandular hairs Unicellular Multicellular Unbranched Branched Unbranched Branched 1- Uniseriate 1- Simple 2- Biseriate 2- Peltate Stellate 3- Pluriseriate 1- Cottony 3- Candelabra 2- Cystolith 3- papillae  A- COVERING TRICHOMES OR NON- GLANDULAR HAIRS I- Unicellular: formed of one cell a- Unbranched or simple: e.g. cottony hair, cystolitic hair b- Branched: as in lavander II- Multicellular: that is formed of more than one cell a- Unbranched or simple: 1- Uniseriate: formed of one row as in Belladonna, stramonium. 2- Biseriate: formed of two rows, each row of one (twin cell) as in Arnica flower, or more cells as in Calendula. 3- Pluriseriate: formed of many rows of cells (Shaggy hair) as in Cumin. b- Branched: 1- Simple branched: with uniseriate body ending in two branches e.g. Tobacco. 2- stellate: group of unicellular hairs 3- Peltate: with very short axis surmounted by a plate-like structure of closely joined cells e.g. olive 4- Candelabra: having uniseriate axis from which arise numerous unicellular branches of hairs e.g. Verbascum. B- GLANDULAR HAIRS I- Unicelluar: not of common occurance, present in Piper. II- Multicellulr: the most common type. They consist of several cells and are classified into: A- Unicellular stalk: and; *Unicellular head e.g. Mentha. *Bicellular head e.g. Digitalis. *Multicellular head e.g. Labiaceous hair in Mentha and clavate hair in Belladonna. B- Multicellular stalk: a- Uniseriate stalk b-Biseriate stalk and biseriate head or compositae type c- Pluriseriate stalk and a head with numerous mostly d- Branched stalk: the branch ending in head