Transcript File

The primary PHOTOSYNTHETIC ORGAN
FUNCTIONS of LEAVES
 PHOTOSYNTHESIS
 Conversion of LIGHT ENERGY into SUGARS

CARBON DIOXIDE (CO2) and WATER (H2O) needed
 RESPIRATION (leaves, stems and roots)
 Breakdown of SUGAR into ENERGY
 ENERGY is needed for GROWTH and to MANUFACTURE
other compounds
 OXYGEN (O2) needed
FUNCTIONS of LEAVES
 TRANSPIRATION
 DIFFUSION of WATER
VAPOR out of leaves
through STOMATA



GAS EXCHANGE
TRANSPIRATIONAL
PULL
COOLING
PARTS of a LEAF
BLADE
 Thin, flattened portion
Midrib
 Large vein running down the center
Veins
 The framework of the leaf
PETIOLE
 STALK that attaches leaf to stem
 ROTATES blade for maximum sunlight
 Greater FLEXIBILITY in wind and rains
SESSILE- NO PETIOLE
 When BLADE attached DIRECTLY to stem
STIPULE
 leaf-like or scale-like APPENDAGE at base of
PETIOLE
AXIL
 ANGLE between leaf and stem
 AXILLARY bud located here
NODE
 Area on stem where leaf arises
Assignment
 You will go outside and find 3 different types of
leaves.
 Tape your leaves to a sheet of notebook paper
 Label the following parts on your leaf:
 Blade
 Petiole or Sessile
 Midrib
 Veins
• When don’t turn in on front table
• Make sure the following coloring pages are done:
• 5-8, 11-14, 49-50, 61-64, 67-70, and 73-78
CLASSIFICATION of LEAVES
 SIMPLE
 One blade /petiole
 COMPOUND –
 Many leaflets/petiole
VENTAION of LEAVES
 Pattern of VEINS in a leaf
 PARALLEL - monocots
 NETTED - dicots
PINNATE- feather
 PALMATE- palm

LEAF ARRANGMENT
 MUST have STEM to determine leaf ARRANGEMENT
 ALTERNATE – one leaf per node
 OPPOSITE – two leaves per node
 WHORLED – three or more leaves per node, each
leaf is the SAME SIZE
ANATOMY of LEAVES
ANATOMY of LEAVES
 EPIDERMIS
 One cell layer thick, top and bottom of leaf
 NO CHLOROPLASTS present
 Cuticle- waxy layer for protection
 Stomata- gas exchange and transpiration
 Guard Cells- surrounds stoma and contains
chloroplast
LEAF MODIFICATIONS
 SUPPORT
 Thick Petioles

Rhubarb and celery
 Captured Gas

Aquatic plants
LEAF MODIFICATIONS
 WATER STORAGE
 Succulents
 FOOD STORAGE
 Scales on Bulbs
 Cabbage and Brussel
sprouts
LEAF MODIFICATIONS
 CLIMBING
 Tendrils (right) on
peas
 Leaf petioles (below)
on Clematis
LEAF MODIFICATIONS
 PROTECTION
 Spines (right)

Cacti
 Bracts (below)

Pointsettia
LEAF MODIFICATIONS
 INGESTION
 Carnivorous plants

Venus Fly Trap (above)

Sundew (left)
Assignment
 Leaf work sheet