TISSUES

• Plant tissues


  • Meristematic tissue
  • Permanent tissue
• Meristematic tissue


  Cells found in the meristems - regions in plants that undergo continuous cell division and growth
• Permanent tissue


  Cells that no longer divide and arise from differentiated cells of the meristematic tissue
• Types of meristematic tissues

  • Apical meristems
  • Lateral meristems
  • Intercalary meristems
• Apical meristems


  Allow plant to grow in length (primary growth), located at the tips of the stems and roots
• Lateral meristems


  Allow plant to grow laterally or increase its diameter or girth (secondary growth) once plant matures, present in region of the stem and roots as circular rings
• Intercalary meristems


  Usually found at the base of a monocot leaf (e.g. grasses) where it could allow the leaf to regenerate after grazing
• Meristems produce cells that either differentiate to become specialized cells of the permanent tissues that lose ability to divide further or continue to be undifferentiated cells of the meristematic tissues
• Types of permanent tissues

  • Dermal tissue
  • Vascular tissue
  • Ground tissue
• Dermal tissue


  Composed of single layer of epidermal cells which provides protection to underlying tissues. The epidermis of the leaf contains openings known as stomata which regulate gas exchange.
• Vascular tissue


  Composed of two specialized conducting cells, xylem and phloem. Xylem transports water from the roots to different parts of the plant. Phloem transports nutrients and organic compounds.
• Types of ground tissue

  • Parenchyma
  • Collenchyma
  • Sclerenchyma
  • Chlorenchyma
• Parenchyma


  Most abundant type of ground tissue cell, thin walled and alive at maturity
• Collenchyma


  Two-three layers of cells located next to the epidermal cells, thick walled and smaller in size than the parenchyma cells
• Sclerenchyma


  Least abundant among the three types, thick walled and dead at maturity, made of stone cells or sclerids and fiber cells
• Chlorenchyma


  Specialized parenchyma cells which contain chloroplast and where photosynthesis occurs, abundant in the leaves of the plant
• Types of root systems

  • Fibrous roots
  • Taproots
• Fibrous roots


  Highly branched roots that lack a central main root, e.g. grasses
• Taproots


  Have one large main root with small lateral or branch roots, can be enlarged for storage, e.g. carrots, turnips, and beets
• Monocot root - the vascular tissue is arranged like a star. Dicot root - the vascular tissue is in circular arrangement.
• Root modifications


  • Haustorial root
  • Pneumatophores
  • Prop root
  • Buttress root
• Haustorial root


  Specialized, modified root of parasitic plants that penetrates into a host plant and functions to acquire necessary nutrients from the host plant they attached themselves to, usually found in hanging plants
• Pneumatophores


  Roots that grow vertically upwards to get oxygen for respiration by plants growing in swamp areas, stores gases to help the plants survive in floods
• Prop root


  Modified adventitious roots that grow downward to provide support to the heavy branches, grow from the stem and penetrate from the ground
• Buttress root


  Large, flared roots that extend horizontally from the base of the tree, providing structural support to provide soil erosion, typically found in the forest or in nutrient-poor rainforest soils, needed for flooded areas as it absorbs the water, and landslides
• Root internal anatomy: Vascular bundle (Stele) - composed of both xylem and phloem and are usually surrounded by a bundle sheath of fibers, Epidermis, Root hairs - greatly increase the surface area and absorbs water and minerals
• Functions of stems


  • Support leaves to maximize light absorption
  • Part of conduit for transport of water, minerals, and organic solutes
  • Storage
• Parts of a leaf

  • Blade
  • Stipules
  • Petiole
  • Node
  • Internodes
• Blade


  Generally broad and flat and ideally suited for the photosynthesis process
• Stipules


  Small paired appendages present at the base of the leaf
• Petiole


  The stalk that joins the blade to the node
• Node


  The area where the petiole is attached to the stem
• Internodes


  The area of the stem between adjacent nodes
• Types of modified stems

  • Bulbs
  • Corm
  • Rhizomes
  • Runners (Stolon)
  • Tubers
  • Tendrils
  • Cladophylls
• Bulbs


  Short flattened stem with many fleshy leaves, found beneath the soil, e.g. onions, garlic
• Corm


  Spherical structure similar to a bulb, e.g. gladiolus
• Rhizomes


  Underground stems that grow horizontally, with the function of storing nutrients and water, e.g. ginger, turmeric
• Runners (Stolon)


  Originates from the elongation of the basal internode and runs horizontally over the ground, e.g. mint, strawberry
• Tubers


  The terminal of the stem is fleshy and stores food, e.g. potatoes
• Tendrils


  Coiled and a delicate part, used for climbing, develop from the axillary bud, e.g. grapevines, watermelons, pumpkin, cucumber