bot119 xylem

• Vascular system is consists of an interconnected network of cells and tissues that function for water and food transport throughout the entire plant body. It also transports hormones and other signaling molecules.
• vascular tissue system is found in:

  • vascular bundles: stem and leaves
  • vascular cylinder: roots
• Xylem transports water and dissolved ions from the roots upwards to the other plant organs.
• Phloem transports metabolites from sources of production to sinks.
• Xylem is the water -conducting system of the plant.
• Xylem transports mineral nutrients, plant hormones, and other regulatory signals.
• True or False. Xylem provides most of the mechanical support for the upright posture and general architecture in vascular plants. True
• Xylem is a complex tissue and is composed of:

  1. tracheary elements- conduction of water and transport of solutes; most common type
  2. xylem fibers- support of the xylem tissue and sometimes storage
  3. xylem parenchyma- food storage and translocation of various substances
• Tracheary elements derived from the term "trachea" a respiratory element
• Tracheary elements has 2 types: tracheids and vessel elements.
• Shape of Tracheary elements?

  more or less elongated
• True or False. Tracheary elements has lignified secondary walls and is dead at maturity. True
• Identify the patterns of secondary wall thickening.

  A) annular

  B) scaliforme

  C) reticulate

  D) spiral

  E) pitted

  F) simple

  G) bordered

  
• Pattern of secondary wall thickening that occurs in the primary xylem of organs that are still elongating. Annular and spiral
• Pattern of secondary wall thickening that is found in vessel members after organ elongation has ended. Scaliforme and Pitted
• What are the regions where secondary wall is not deposited?

  pits
• Identify the type of pits

  A) simple

  B) bordered

  C) half-bordered

  
• Pitting patterns in tracheary elements:

  1. Alternate- pits arranged in diagonal rows
  2. Opposite- oval-bordered pits arranged horizontally
  3. Scalariform- elongated pits arranged in ladder-like series
• Identify the pitting patterns in tracheary elements.

  A) alternate

  B) opposite

  C) scalariform

  
• Tracheids- type of tracheary elements found in both angiosperms and gymnosperms.

  Vessel elements- type of tracheary element common in angiosperm but rare in gymnosperms.
• Tracheids are more primitive than vessel elements
• Tracheids

  • shape: elongating and tapering
  • lack perforiations
  • contain pits
• Vessel elements

  • wider than tracheids (more efficient in conducting water)
  • elongated but shorter than tracheids and are connected to end-to-end to form continuous columns called vessels.
  • perforations at their walls called perforiation plates
• Types of perforation plates

  A) simple perforation plates

  B) scalariform perforation plates

  C) reticulate perforation plates

  D) foraminate perforation plates

  
• Types of perforation plates:

  A) simple

  B) scalariform

  C) foraminate

  D) reticulate

  
• True or False. Xylem fibers are specialized supporting elements. True
• Xylem fibers shape: long with commonly lignified secondary walls
• Xylem fibers has thicker walls than tracheids.
• Xylem retain protoplasts at maturity so they can function as a storage.
• 2 principal types of xylem fibers:

  1. libriform fibers
  2. fiber-tracheids
• Libriform fibers have simple pits, longer, and commonly thicker walls
• Fiber-tracheids have bordered pits with lenticular slit-like apertures, shorter, and thinner walls.
• Xylem parenchyma- living cells found in the xylem and is present in both primary and secondary xylem (axial and ray parenchyma)
• Xylem parenchyma has a thin primary cell wall but in secondary xylem, they often have a secondary wall.
• Xylem parenchyma primarily stores starch or fat but also tannins and crystals.
• give the precursor of:

  1. primary xylem- procambium
  2. secondary xylem- vascular cambium
• protoxylem- earlier formed xylem

  metaxylem- later developed xylem
• Protoxylem differentiates in parts of the primary plant that have not completely grown yet.
• Protoxylem contains relatively few tracheary elements embedded in parenchyma that has annular/spiral thickenings
• Metaxylem first differentiates in still growing primary plant body but matures largely after elongation is completed.