Botany (Plant Tissues): Exam 1

• What are meristematic tissues?

  Tissues that are actively dividing
• Parenchyma (simple tissue, meristematic)

  A typical plant cell, has a thin primary wall with no secondary wall. Do not stain red with phloro-HCl.

  
• What is the function of the parenchyma?

  Specialized for photosynthesis and the storage of food.
• Collenchyma (simple tissue, meristematic)

  Uneven primary wall, do not stain red. Thick at the corners causing them to be almost square shaped.

  
• What is the function of the collenchyma?

  Provide support and/or flexibility to actively growing parts of the plant.
• Schlerenchyma (simple tissue, meristematic)

  Provides structural support. Contains a large amount of lignin and has two cell walls. Cells are often dead at maturity, stain red with phloro-HCl.

  
• Schlerenchyma (Fibers)

  Are longer than they are wide, typically dead. Secondary cell wall is strengthened with lignin. Have a lumen where the cytoplasm once was. Stain red.

  
• Schlerenchyma (Sclereids)

  Dead, have a lumen where the cytoplasm once was. Large portion of the secondary wall is lined with lignin. Helps to deter herbivory and is used as a seed coating.

  
• Epidermis (complex, meristematic)

  The outermost layer on the plant, usually one cell thick. Have hairs: trichomes (stem) and root hairs which are projection of the epidermal cells.

  
• What makes up the epidermis?

  trichomes, stomata (guard cells), subsidary cells

  
• Xylem (complex, meristematic)

  Support, food and mineral conduction, and some storage. Composed of parenchyma, fibers, vessels, tracheids, and rays of parenchyma.

  
• Xylem Vessels


  Long tubes made of vessel elements, have bar like strips at the end known as perforation plates. Have pits in their side walls.

  
• Xylem Tracheids

  Narrow, tapered at the ends. Have pits in their end and side walls.

  
• What to the xylem vessels and tracheids share in common?

  Primary and secondary walls, secondary wall with lined with lignin that stains red. Both are dead are maturity and have a lumen thats empty of cytoplasm. Patterns of lignin are embedded into the secondary wall
• Phloem (complex, meristematic)

  Conducts dissolved foods such as carbohydrates. Source and sink relationships determine the direction of transport in the phloem. Direction of transport is up, down, and sideways.Composed of parenchyma cells for storage, fibers, sieve tubes, companion cells, and rays of parenchyma in wood.

  
• What are sources of carbs?

  Photosynthesizing leaves, underground storage areas that are exporting, and mature structures that are also exporting
• What are sinks of carbs?

  Growing leaves, roots, stems, buds, fruits, and flowers
• Phloem Sieve Tubes

  lack a nucleus, are wider in diameter, site of transport, and have sieve plates at the end
• Phloem Companion Cells

  have a nucleus, narrow in diameter, aid in the transport process
• What are companion cells and sieve tube cells similarities?

  Both only have primary walls and are alive at maturity
• Xylem and Phloem in Gymnosperms

  Xylem: has tracheids but no fibers (making gymnosperms a softwood)Phloem has albuminous cells instead of companion cells, but both are similar
• Periderm (complex, meristematic)


  The outer bark of woody plants.Composed of the phelloderm, cork cambium, and cork cells (dead @ maturity, have suberin for waterproofing)

  
• Secretory Tissue

  Release nectar, oil, resin, latex, wax, poison, enzymes, and mucilage