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Leaves (Morphology and anatomy of others leaf types (Succulent leaves (Are…
Leaves
Morphology and anatomy of others leaf types
Succulent leaves
Good in desert habitat
Families
Crassulaceae
Portulacacea
Aizoacea
Are
Thick
Fleshy
Cylindrical or spherical
Good at conserving water
Not great at photosynthesis
Retention
Reduces CO2 uptake
Lack air space
Photosynthesis occurs deep in plant
Sclerophylous Foliage leaves
Must produce
More sugar than used
Most leaves
Soft
Flexible
Edible
Some species
Are perennial
#
Leaves of conifers
Sclerophyll leaves
Have
Thick cuticle
Thick epidermis cell walls
Thick Hypodermis cell walls
Unpalatable chemicals
Always simple leaves
Few forms
Needle
Scale like
Perennial
Bud Scales
Provide proection to apical meristem
petiole is short or absent
Often produce corky bark
Spines
#
Cacti have two leaves
Microscopic green leaves
Spine clusters
axillary buds
Cacti
Good source of water for animals
Spines protect them from animals
Have no blade
Are needle shaped
No mesophyll, parenchyma, or vascular tissue
Composed of dead fiber
Tendrils
Form of modified leaf
Grow indefinitely
Able to sense contact
Grows around objects
Leaves with Kranz Anatomy
occurs in C4 plants
lack palisade parenchyma
lack spongy mesophyll
have bundle sheaths
composed of chlorophyllous cells
Insect traps
Digest insects to get nitrogen
Active traps
Move during capture
Drosera
#
Passive traps
incapable of movement
Nepenthes
Lamina is tubular not flat
Epidermis is absorbative
Throat of pitcher
has numerous trichomes
Similar to foliage leaves
External structure of foliage leaves
Leaf Blade
Flat and light harvesting
AKA lamina
Lower side is
Dorsal surface
Large veins protrude
AkA Abaxial surface
Upper side
Ventral surface face
AKA adaxial
Usually smooth
Petiole
Stalk
Holds blade in light
Flexible petioles
Allow leaf to flap in wind
Cools down leaf
Brings fresh air to surface
Difficult for insects to mount
Abscision zone
Perpendicular to petiole
Cuts leaf off when needed
Via use of enzymes
Form leaf scars
Monocots, ferns, and cycads don't have leaf scars
Sessile leaf
No self shading issue
found in extremely sunny regions
Leaves often closely packed
Good for water conservation
Long,small, and narrow
Sheathing leaf base
Leaf base wrapped around stem
Is flexible
Simple leaf
blade is one part
susceptible to wind damage
Great number of photosynthetic cells
Compound leaf
Leaf blade divided in multiple parts
Leafets
many small blades
Attached to petiule
Palmately compound
leafets attached to same spot
Pinnately compound
Leafets attached individually along rachis
Large number of
Petolules
edges
non-photosynthetic rachis
Veins
Distribute water from stem into leaf
Collect sugars
Carry them to stem
For use
For storage
Reticulate venation
Netted pattern
present in angiosperm and eudicots
Parallel venation
Large veins
Run side by side
Not many obvious interconnections
Internal Structure of Foliage Leaves
Epidermis
Transpiration
Water loss through epidermis
Issue if soil is dry
Contain
Epidermal cells
Guard cells
Trichomes
Glandular
Non-glandular
Stomata
Crypts
Epidermis depressed in to leaf
Cutin and wax
Prevent spores from sticking to plant
Prevent blockage from water accumulation
Trichomes
Provide some shade to upper epidermis
Deflect light
On lower epidermis
Prevent rapid are flow
Slow water loss
ward off insects
Typically hairy
Mesophyll
Is ground tissue
Palisade parenchyma
Typically on upper surface
Main photosynthetic tissue
Separated slightly with intercellular space
Normally one layer thick
Spongy mesophyll
Loose aerenchyma
Allows CO2 to diffuse rapidly
In center of plants or is lacking
Vascular Tissue
Between Palisade and Spongy Mesophyll
Contains large mid rib
Lateral veins branch from mid rib
Narrow into minor veins
Minor veins
Release water from xylem
put sugar into phloem
Lateral vein and mid rib
Involved in conduction
Change with size
Always
Contain xylem on upper side
Contain phloem on lower side
Have sheath bundles
Veins have
Bundle sheath extension
Provide rigidity
Petiole
Are transition from
Stem to lamina
not aerenchymatous
Tissue arrangement differs
at each end
Stipules
Two small tissue flaps at base
Protect apical meristem in young leaf
die early
Provide photosynthesis in some plants
Leaf traces
Vascular bundles
Initiation and development of leaves
Basal Angiosperms and Eudicots
Leaf primordium
cells at base of meristemt
that grow out
extend upward as narrow cone
Then thickens
creates mid rib
Once taller than shoot apical meristem
Primordium consist of
leaf protoderm
leaf ground meristem
is meristematic
has dense cytoplasm
has small vacuoles
Cells grow outward
Creating lamina
Monocots
Leaves initiated by
Expansion of shoot apical meristem
Apical meristem cells grow
adjacent to the primordium
Becomes part of primordium
Becomes hood shaped
Primordium becomes a cylinder
Encircles shoot apical meristem
Some plants
Lamina is broad like a eudicot
Grasses and lilies
Have linear leaves
grow continually
No predetermined size
Lamina grow by meristem
Cells remain active mitotically
Great at regenerating
Concepts
Leaves
Provide Protection
Bud scales
Spines
Provide Support
Tendrils
Provide Storage
Fleshy leaves of bulbs
Contain only Primary tissue
Spines lack leaf blades
Drosera are Eudicots
The Berberis in the picture is a compound leaf
