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Screen Shot 2020-09-23 at 11.38.34 PM Leaves, almost all species of…
Leaves
External Structure of Foliage Leaves
function
photosynthesis
must not allow
fungi, bacteria
animals
not be effective sails
leaf blade
light-harvesting portion
simple leaf
one part blade
compound leaf
blade
several individual part
dorsal surface
blade's lower side
larger veins protude
ventral surface
upper side
smooth
petiole
holds blade
into the light
sessile leaf
no petiole
sheathing leaf base
Internal Structure of Foliage Leaves
Epidermis
reasonably waterproof
but
simultaneously translucent
hairy
provide footholds
trichomes
deflect excessive sunlight
provide shade
makes difficult
for animals/insects to
chew on
walk on
stomata sunken
nonmoving air
cutin
retain water
smooth, slippery surface
prevents spores from sticking
allows spores to be washed off
Mesophyll
palisade parenchyma
layer of cells
at the upper surface
exposed to
intercellular space
spongy lower portion
aerenchyma
permits CO2 to
diffuse rapidly
into interior part
ground tissue interior to epidermis
Petiole
part of leaf
transition between
stem
lamina
leaf traces
3 or more vascular bundles
stipules
2 small flaps
protect the shoot apical meristem
contributes in photosynthesis
Vascular Tissue
Between
palisade parenchyma and spongy mesophyll
midrib
lateral veins
minor veins
xylem and phloem
bundle sheath
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Initiation and Development of leaf
Basal Angiosperm and Eudicots
leaf primordium
extend upward
leaf protoderm
increases in thickeness
bulk of midrif
lamina expansion
stomata, trichomes and vascular bundles differenciates
petiole become distinct
becomes dormant part
of auxillary bud
Monocot
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like those of eudicots
constant basal eplosion
lamina becomes broad and expanded
Morphology and Anatomy of other leaf Types
Succulent leaves
permit plants to
survive in desert
suface-to-volume shape
advantageous in
water retention
reduce CO2 intake
spherical shaped leaves
Thick and fleshy
Sclerophyllous Foliage leaves
must produce more sugar
by photosynthesis
or plant loses energy
soft ,flexible,edible
some are perennial
cuticle
very thick
waxes
abundant
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Leaves of Conifers
sclerophylls
thick cuticle
perennial
plants are evergreens
Needdles
large, broad scales
held away from stem
bud scales
Tougher and waxier
to be protective
on exposed portions
evolutionary conversion
small and rarely compound
no risk of
mechanical wind damage
short petiole
produce
thin layer of corky bark
spines
modified leaves of auxilary bud
Tendrils
grows indefinitely
cell capable of sensing contact
highly modified leaf
no leaf blade
Leaves with Kranz Anatomy
C4 photosynthetic plant
lack
palisade parenchyma
spongey mesophyll
prominent bundle sheath
Insect Traps
ability
trap and digest insects
obtain nitrogen
habitat
poor in ammonia and nitrate
lamina is tubular
secretes
watery digestive fluid
absorptive epidermis
in digestive region
throat of the pitcher
numerous trichomes
secrete a sticky digestive liquid
easier for insect to walk in
almost all species of conifers, leaves are sclerophyll
monocot leafs also forms leaf primordium
Leaves