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Leaf (Internal Structure of Foliage Leaves (Epidermis (stomata (cutin…
Leaf
Internal Structure of Foliage Leaves
Epidermis
large surface area
water loss
transpiration
guard cells/ trichomes (glandular or nonglandular) abundant
stomata
sunken into epidermal cavities
cutin
retain water/ protection
Mesophyll
palisade parenchyma (palisade mesophyll)main photosynthetic tissue
usually one layer thick
spongy mesophyll
lower portion of leaf
loose aerenchyma
CO₂ diffusion
Vascular Tissues
midrib (midvein)
lateral veins
minor veins
loading sugar into phloem
release water from xylem
conduction/ supportc onduction/ support
bundle sheath
fibers around vascular tissue
bundle sheath extension
Petiole
transition b/t stem & lamina
leaf trances
1,3,5+ vascular bundles
Stipules
two small flaps
some apical meristem cells grow with primordium
Morphology and anatomy of other leaves
Insect traps
Succulent leaves
Thick and fleshy
Portulacaceae
Lewisia
Portulaca
Aizoaceae
ice plant
Crassulaceae
Sedum
Kalanchoe
active traps
move during capture
Sundew leaves
passive traps
incapable of movement
pitcher leaves
traps & digests insects
insect ivory
obtain nitrogen
Sclerophyllous Foliage Leaves
foliage must produce more sugars
limits sclerenchyma
Hardness
resistant
soft
Flexible
edible
sclerenchymatous leaves
Hardness
Resistant
fungi
freezing temperatures
animals
ultraviolet light
ultraviolet light
Leaves of Conifers
sclerophylls
thick cell walls
unpalatable chemical
thick cuticle
Small, flat , scale-like needles
Bud Scales
primary protective
small and rarely compound
petiole short or absent
tough and waxy
picture
Spines
axillary buds
needle shaped
no mesophyll parenchyma
no vascular tissue
closely packed fibers
Tendrils
grow indefinitely
can sense contact
grows around the object
does not form lamina
External Structures of Foliage Leaves
Petiole
stalk
stalk holds blade out into light
abscission zone
leaf base/ usually in petiole cells release enzymes that weaken cell walls
cuts off leaf
Ventral Surface
upper side/ adaxial
Dorsal Surface
lower side/ abaxial side
Leaf Blade (also called lamina)
light harvesting portion
simple leaf
Blade one part
compound leaf
blade divided into several parts leaflets=many small blades attached to petiolule & the extension rachis
pinnately compound
leaflets attached individually to rachis
palmately compound
leaflets attached at same point
Sessile Leaf
bundles of vascular tissue
Veins are side by side
Monocots
Parallel Ventilation
sheathing leaf base
reticulate venation
distribute water/ collect sugars
angiosperms
eudicots
no petriole
netted pattern
Initiation and Development of Leaves
Basal Angiosperms and Eudicot
produced by shoot meristeml eaf primordium
leaf primordium
causes protrusion
Ground leaf meristem
differentiation
merismatic
primary xylem
primary phloem
provascular tissue
leaf protoderm
shoot apical meriosperms
hood-like shape
becomes a cylinder
completely encircles shoot apical meristem
some apical meristem cells grow with primordium
Monocot
shoot apical meristem expansion
