Plant Morphology and Anatomy

• TWO TYPES OF PLANT TISSUES BASED ON THEIR ORIGIN

  1. Meristematic or Embryonic Tissues
  2. Permanent Tissues
• Meristematic Tissues - They are responsible for the production of more cells.
• Meristematic Tissues - The new cells produced are typically small, each with a proportionately large nucleus in the center and tiny vacuoles or no vacuoles at all.
• Meristematic Tissues - As these tissues mature, they assume different shape and sizes related to the cells’ ultimate function
• Label the photo

  A) Apical Meristem

  B) Intercalary Meristem

  C) Lateral Meristem

  
• Apical Meristem - Tip of shoot and root
• Apical Meristem - Increased in length as apical meristems produce new cells
• Apical Meristem - Primary Meristems: Protoderm, ground meristem, procambium
• Lateral Meristems - Increases the girth or diameter of plants
• Lateral Meristems - Found on some roots and stems
• Lateral meristems - are found in dicot plants (vascular cambium and cork cambium
• Intercalary Meristems - Found in vicinity of nodes
• Intercalary Meristems - Increase the length of stems
• Intercalary Meristems - Short-lived meristem
• Permanent Tissues - Tissues that are derived from the meristems that have already assumed various shapes and sizes related to their specific functions as they develop and mature
• Permanent Tissues - They are usually non-dividing cells with few exceptions
• SIMPLE PERMANENT TISSUES

  1. Parenchyma
  2. Collenchyma
  3. Sclerenchyma
  4. Epidermis
  5. Cork
  6. Secretory Tissues
• Parenchyma - These are the most abundant of all cell types found in almost all major parts of higher plants.
• Parenchyma - The cells are more or less spherical in shape when newly produced
• Parenchyma - But once it matures they push against each other and their thin pliable walls are flattened at the point of contact. As a result they assume various shapes
• Collenchyma - This tissue is composed of thick-walled cells of uneven thickness.
• Collenchyma - This tissue is composed of thick-walled cells of uneven thickness.
• Collenchyma cells - often occur just beneath the epidermis Typically they are longer than they are wide and their cell walls are pliable as well as strong They are usually smaller than parenchymal cells
• Sclerenchyma - Characterized by cells that are thick and tough-walled.
• Sclerenchyma - These are normally impregnated with lignin.
• Most sclerenchyma cells - are dead at maturity.
• Sclerenchyma - They function as supporting tissues in plants
• 2 Types of Sclerenchyma

  1. Sclereids
  2. Fibers
• Sclereids - May be distributed randomly in other plant tissues. Example is the gritty texture in chico and pears is due to sclereids or stone cells present in the fruit
• Fibers - May be found in association with different tissues. They are usually much longer than broad and have a tiny cavity or lumen in the center of the cell
• Epidermis - This is the outermost layer of the cells found in all young plant organs.
• Epidermis - This is usually one cell thick although maybe of several layers in some.
• Epidermis - Most epidermal cells secrete a fatty substance called cutin
• Epidermis - Cutin form a protective layer called cuticle.
• Epidermis - Hairs of the trichomes of different nature occur on the epidermis of above-ground plants.
• Cork - Serves as the outermost covering of old stems and old roots of woody dicot plants.
• Cork Serves - This consist of several layers of dead cells when mature.
• Cork Serves - Their cell walls are impregnated with a waxy substance called suberin which renders them impermeable to substances such as water.
• Secretory Tissues - Composed of secretory cells that produce hormones or wastes products no longer important to the plant.
• Most common secretory tissues - are those that secretes nectar in flowers, oil in citrus, menthol in mint leaves, mucilage, latex and resins in pine trees.