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Leaves (Morphology and anatomy of other leaf types (Leaves of conifers…
Leaves
Morphology and anatomy of other leaf types
succulent Leaves
thick and fleshy
favor water conservation
reduces capacity for CO2 intake
mesophyll contains few air spaces
photosynthesis occurs deeper
Sclerophyllous Foliage leaves
produce more sugars by photosynthesis
soft, flexible, edible
very this cuticle
abundant waxes
Leaves of conifers
sclerophylls
thick cuticle
epidermis and hypodermis
thick walls
always simple
mostly perrenial
thick needles ofter
Bud scales
form tight layer around stem tip
protects against cold
role is protection not photosynthesis
small, rarely compound
must stay close to stem
Spines
auxiliary buds of cacti
modified leaves of auxiliary buds
protect cacti from animals
protects plant water supply
Tendrils
grow indefinitely
sense contact with objects
stops growth with side facing object
grow around solid objects
Leaves with Kranz Anatomy
C4 photosynthesis
adapts C4 plants to arid environments
Insect traps
use bugs as N source
have numerous stomata and bundles
similar to foliage leaves
adapted to digest insects
trigger hairs stimulate trap
external structure of foliage trees
allow photosynthesis
Leaves absorb CO2 and light
conversion to carbohydrates
Leaves flat and wide
allows maximum absorbtion
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Lamina
flat harvesting part
Dorsal surface
Leaves "backbone"
petiole
stock
holds the leaf out into the light
prevents shading
allows leaf to flutter in the wind
abscission zone
cells cut off leaf when life is over
sessile leaves
small/ long and narrow
close packing traps H2O
grow in sunny regions
Blade types
Simple
Blade of one part
Compound
Blade of several parts
Has many small blades
Leaflets
more blades protect the plant
blades attached along rachis
better adapted for wind
Some produce both types
Internal structure of Foliage trees
epidermis
outer layer of leaf
controls in and out of leaf
Outer walls made with cutin
makes wall impermeable to H2O
cutin builds up as a pure layer
stomata allows entry
Parenchyma cells
mesophyll
interior leaf ground tissues
palisade parenchyma
photosynthetic tissues
1-5 layers thick
lower layer
spongy mesophyll
Vascular tissues
Mid-rib
where lateral veins emerge
minor veins
H2O released
help support the leaf
bundle sheath
Petiole
transition from stem to lamina
Leaf traces
branch from stem vb
divide to up to 10-20 bundles
Large in palms, lillys
Initiation and Development of Leaves
Basal angiosperms of leaves
leaf produced by shoot apical meristem
base of meristem
leaf primordium
extends upward as cone
becomes thicker
compound leaf
initiate leaflets
perenial plants
started summer before maturity
Monocots
leaf primordium
one leaf grows after another
succulent stems store water
more apical meristem cells involved
lamina becomes broad and expanded
some have no predetermined size