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Ch. 6; Leaves (Morphology and Anatomy of Other Leaf Types (Bud Scales…
Ch. 6; Leaves
Morphology and Anatomy of Other Leaf Types
Succulent Leaves
Thick and fleshy
lack air spaces which help retain water, and mesophyll transparent.
Underground leaves, exposed leaf tips.
Bud Scales
Protection
modification of leaves.
small, simple leaves.
Folded over and close to stem, small or lack petiole
Tough, and waxy.
Spines
modified leaves
no mesophyll parenchyma or vascular tissues
Mesophyll consists of packed fibers
Lignin in fibers make them hard and resistant to decay.
Tendrils
Modified leaves.
hard and resistant to decay.
Grow, and coil around objects.
Leaves with Kranz Anatomy
Lack palisade parenchyma and spongy mesophyll
Prominent bundle sheaths surrounded by mesophyll layer.
CO2 transport require kranz anatomy.
C4 Plants
Insect Traps
Trap and digest inscts
numerous stomata and vascular tissue
Mesophyll contains aerenchyma and chlorenchyma
Lamina is tubular and secrete digestive fluid.
Leaves of Conifers
Thick cuticle
Epidermis and hypodermis have thick walls
Few forms
Needles
Small Scale
Broad scales
Perennials, (evergreens)
Can produce new phloem, but not new Xylem
Sclerophyllous Foliage Leaves
Thick, and waxy.
External Structures of Foliage Leaves
Petiolate Leaf
Holds leaf out into light.
Prevents shading from other leaves.
Allows leaf to flutter in wind.
Helps to prevent insects from landing on leaves
Prevents CO2 depletion
Sessile Leaf
Lack Petiole
Close Packing of leaes
Sheathing leaf base allows blade to flutter.
Simple or compound leaves.
Veins dispute water, and allow sugars to be transported.
Reticulate venation occur in netted pattern
Parallel venation run side by side.
Internal Structure of Foliage Leaves
Epidermis
Water resistant
Transluncent
Allows entry of CO2
Mesophyll is the ground tissue interior to leaves.
Palisade parenchyma is the main photosynthetic tissue
Spongy Mesophyll permits CO2 to diffuse away from stomata into leaf interior.
Vascular Tissues
between palisade parenchyma and Spongy mesophylle
Lateral veins emerge from mid-rib branch out into minor veins
Minor veins release water from xylem and load sugar into phloem
Mid-rib and lateral veins conduct and support leaf.
Bundle sheath help protect against insect .
Petiole is the transition from stem to lamina.
Leaf Traces- vascular bundles
Stipules
Initiation and Development of Leaves
Basal Angiosperms and Eudicots
leaf primordium
Lamina Expansion
Monocots
Leaf primordial form.
Apical meristem cells grow upward giving shaping a hood.
Sheathing leaf base is formed and give rise to lamina.
shoot apex enlarges and initiates nex leaf primordium
