BOT2601 Exam Questions
Write brief notes on distictive differences of the following leaves and state their habitat:
• Xeromorphic leaves
o Reduction in leaf size.
o increased thickness of the outer walls of epidermal cells
o increased thickness of cuticle
o increased trichome density
o reduction in stomatal pore area
o stomata recession below the blade surface (↓ loss of water)
o Increase in mechanical cells
o Wall lignification
o Increase succulence and water storage capacity
o Accumulation of mucilage (tolerate dehydration and water stress)
• Ericoid leaves
o Reduction in leaf size in families, which results in production of amll leaves of
different form and shape
o Needlelike or scalelike projections
o Reduction in leaf surface – formation of short, linear leaf size (ericoid =
Ericaceae)
o Extreme ecological specialisation
o Stomatal grooves that extend the entire length of the lower surface
o Trichomes fill the grooves or be located along lower surface
o Lamina has prominent enrolled margins or cyclindrical in outline
o Exhibit parallel changes in internal anatomy = general foliar sclerification
• Succulent leaves
o Epidermal cells thickened, heavily cutinized
o Mucilaginous substance prominent to deliver huge amounts of water
o Colorless storage cells, large and thin-walled
o Walls reinforced to prevent colapse when turgor is ↓
o Little to no sclerenchyma
o
• Sclerophyllous
o Dry environment
o Broad lamina
o Leathery leaves
o Thick leaves with high lignified cells and cutinized epidermal walls
o Dense venation
o Individual vascular bundles increased in size
o Trichome density prominent (sometimes lignified)
o 1 or more layers of heavily lignified cells below epidermis = forms hypodermis
o Sclerified cells ↑ = well-developed and lignified bundle sheath around the
veins
o Sclerenchyma support
Write brief notes on distictive differences of the following leaves and state their habitat:
• Xeromorphic leaves
o Reduction in leaf size.
o increased thickness of the outer walls of epidermal cells
o increased thickness of cuticle
o increased trichome density
o reduction in stomatal pore area
o stomata recession below the blade surface (↓ loss of water)
o Increase in mechanical cells
o Wall lignification
o Increase succulence and water storage capacity
o Accumulation of mucilage (tolerate dehydration and water stress)
• Ericoid leaves
o Reduction in leaf size in families, which results in production of amll leaves of
different form and shape
o Needlelike or scalelike projections
o Reduction in leaf surface – formation of short, linear leaf size (ericoid =
Ericaceae)
o Extreme ecological specialisation
o Stomatal grooves that extend the entire length of the lower surface
o Trichomes fill the grooves or be located along lower surface
o Lamina has prominent enrolled margins or cyclindrical in outline
o Exhibit parallel changes in internal anatomy = general foliar sclerification
• Succulent leaves
o Epidermal cells thickened, heavily cutinized
o Mucilaginous substance prominent to deliver huge amounts of water
o Colorless storage cells, large and thin-walled
o Walls reinforced to prevent colapse when turgor is ↓
o Little to no sclerenchyma
o
• Sclerophyllous
o Dry environment
o Broad lamina
o Leathery leaves
o Thick leaves with high lignified cells and cutinized epidermal walls
o Dense venation
o Individual vascular bundles increased in size
o Trichome density prominent (sometimes lignified)
o 1 or more layers of heavily lignified cells below epidermis = forms hypodermis
o Sclerified cells ↑ = well-developed and lignified bundle sheath around the
veins
o Sclerenchyma support
