module 3

• Tissues


  Group of cells performing similar functions. Cellular organization between a cell and a complete organ. Ensemble of analogous cells that carry out specific function.
• Meristematic tissues


  Tissues which are responsible for the production of more cells. Composed of actively dividing cells and thus are permanent regions of growth.

  
• Primary growth


  Increase in length of the plant. Occurs at the tips of the stems and roots. Takes place at the apical meristems.
• Secondary growth


  Increase in the girth of the plants. Occur only on gymnosperms and woody eudicots. Takes place at the lateral meristems.
• Apical meristem


  • Meristematic tissues found at, or near, the tips of the root, and shoots, which increase in length as it produces new cells and primary tissues. Includes protoderm, ground meristem, and procambium.

  
• Lateral meristem


  • Produce tissues that increase in girth of roots and stems. Includes vascular cambium and cork cambium.
• Intercalary meristem


  • Develop at intervals where the tissues add to the stem length. Like apical meristems, they also increase the length of stems.
• Permanent tissues


  Tissues that assume various shapes and sizes related to their functions as they develop and mature, after the production of cells at the meristems.
• Tissue systems


  • Simple tissues, complex tissues
• Ground tissue


  • Acts as food storage, provides support and protection, site of cellular regeneration and photosynthesis. Includes cortex and pith.

  
• Parenchyma


  The most abundant cell type found in almost all the major parts of higher plants. Primary component of ground tissues. Site of basic plant functions like photosynthesis, secretion, and storage.

  
• Chlorenchyma


  • Chloroplast containing cells that specializes on photosynthesis.

  
• Aerenchyma


  • Tissues with extensive connected air/intracellular spaces.
• Collenchyma


  • Provide support in soft, non woody plant organs like shoot tips and young petiole. Have primary cell walls that are unevenly thickened and especially thick in the corners. Walls exhibit plasticity and cells can elongate.
• Sclerenchyma


  • Have thick, tough secondary walls, impregnated with lignin. Provides support and strengthen non-extending regions of plants. Includes sclereids.
• Fibers


  • Long, slender cells that occur in single strand or bundles in the wood, inner bark, and leaf ribs of flowering plants. Have a tiny cavity or lumen in the center of the cell. Provide elasticity and resistance to attacks.
• Dermal tissue


  • Provides protection and prevents water loss. Includes epidermis, cuticle, trichomes, and stomata.
• Periderm


  • Replaces the epidermis in stems and roots of older woody plants. Forms the outer protective bark. Composed of cork cells and cork parenchyma cells.
• Vascular tissue


  • Transports water, minerals and food. Includes xylem and phloem.

  
• Xylem


  • Conducts water and minerals. Includes tracheids and vessel elements. Has primary xylem (protoxylem and metaxylem) and secondary xylem.
• Phloem


  • Distributes water and minerals. Composed of sieve-tube members and companion cells. Provides structural support.