[3] Seagrasses

• Seagrasses are angiosperms, or flowering plants
• Holdfast analogy in seagrasses

  
  

  Roots
• Stipe analogy in seagrasses

  Stem
• Frond analogy in seagrasses

  Leaves or blades
• Instead of sporophyte and gametophyte stages, seagrasses simply disperse seeds into the water from their fruits
• While seaweeds rely on diffusion for nutrient transport, seagrasses have a xylem and phloem
• Seagrass roots grow as rhizomes (fine hair-like roots)
• Roots grow along the nodes of horizontal stems

  
• Label the ff. figure

  A) Lacunae

  B) Blade

  C) Flower

  D) Sheath

  E) Node

  F) Internode

  G) Vertical stem

  H) Roots

  
• Main area where the blade of leaves grow

  Sheath
• Cells with very large spaces to allow for easy oxygen diffusion

  Aerenchyme tissue
• Lacunae are large spaces that allow for better diffusion of oxygen throughout the plant
• Lacunae only allow oxygen, not water, to diffuse
• Along with oxygen, bacteria and fungi can enter the lacunae
• Air bladder analogy in seagrasses

  Lacunae
• Seagrasses can produce tannins in their tissue to deter bacteria, fungi, and herbivores
• Label the ff. seagrass leaf shapes

  A) Blade-like

  B) Tubular or Cylindrical

  C) Paddle shaped

  
• T or F: Seagrasses reproduce completely asexually

  False
• Hydrophilous pollination disperses pollen via water currents
• To aid in hydrophilous pollination, flowers produced by seagrasses are hydrophobic
• Involves the development of young inside the parent to ensure further survival

  Viviparity
• Seagrasses can undergo asexual reproduction by producing runners
• Ecological Roles of Seagrasses

  1. Important habitats for different types of organisms
  2. Primary producers
  3. Sediment stabilizers