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Leaves (External Structure of Foliage Leaves (Leaf blade (Flat, Light…
Leaves
External Structure of Foliage Leaves
Leaf blade
Flat
Light harvesting
Lamina
Dorsal surface
Blade's lower side
Larger veins
Protrude like backbones
Abaxial side
Ventral surface
Upper side
Adaxial
Smooth
Petiole
Stalk
Holds blade into light
Sessile leaf
Leaves don't have petiole
Simple leaf
Blade of just one part
Compound leaf
Blade divided several parts
Veins
Bundles of vascular tissue
Leaf scar
Protective scar tissue
Morphology & Anatomy of Other Leaf Types
Succulent leaves
Thick & fleshy
Favors water conservation
Sclerophyllous Foliage Leaves
must produce more sugars
by photosynthesis
Leaves of Conifers
contain unpalatable chemicals
always simple
never compund
Bud scales
Small
Rarely compund
Spines
Cactus spines
Modified leaves of axillary buds
Tendrills
Form of modified leaf
Grow indefinitely
Contain cells that are:
capable of sensing contact w/ objects
Leaves with Kranz Anatomy
C4 photosyntheis
Insect traps
The ability to trap & digest insects
Active traps
Move during capture
Passive traps
Incapable of movement
Internal Structure of Foliage Leaves
Epidermis
Reasonably waterproof
Translucent
Transpiration
Water loss through epidermis
Entry of carbon dioxide
Mesophyll
Ground tissues interior to epidermis
Palisade parenchyma
Layer of cells
Along upper surface of leaf
Photosynthetic tissue
Spongy mesophyll
Lower portion of leaf
Vascular Tissues
Between palisade parenchyma & spongy mesophyll
Midrib
Midvein
Lateral veins
Emerge branch into narrow:
Minor veins
Bundle sheath
Fibers arranged as a sheath
Petiole
Transition between stem & lamina
Stipules
2 small flaps of tissue
Initiation and Development of Leaves
Basal Angiosperms & Eudicots
Leaf predormium
Extends upward
Narrow cone
Monocots
Initiated by:
expansion of apical shoot meristems
:
