Plant Tissues

• epidermal tissues:

  • cover the whole plant
  • covered with a waxy cuticle, which helps to reduce water loss by evaporation
• upper epidermis is transparent so that light can pass through it to the palisade layer
• palisade mesophyll:

  • the part of the leaf where most photosynthesis takes place
  • has lots of chloroplasts
  • nor the top of the leaf to get the most light
• spongy mesophyll:

  • in the leaf
  • has big air spaces to allow gases to diffuse in and out of cells
• xylem and phloem:

  • transport things like water, mineral ions, and food around the plant
  • form a network of vascular bundles, which deliver water and other nutrients to the entire leaf and take away the glucose produced by photosynthesis.
  • help support the structue
• meristem tissue:

  • found at the growing tips of roots and shoots and is able to differentiate into lots of different kinds of cell, allowing the plant to grow
• The tissues of leaves are also adapted for efficient gas exchange.

  The lower epidermis is full of little holes called stomata, which let carbon dioxide diffuse directly into the leaf.

  The opening and closing of stomata is controlled by guard cells in response to environmental factors.

  The air spaces in the spongy mesophyll tissue increase the rate of diffusion of gases.