Lovely, Lovely Leaves
Leaf arrangement
OppositeDecussate
Leaf arrangement
Alternate Basal rosette
Function and Shape
Leaf Venation
Net venationParallel venation
Petiole
Sessile leaves
Axillary Buds
Simple & Compound Leaves
NB. position ofaxillary bud
Leaf Sheath & Ligule (monocots)
Sheath
Ligule
•Intercalary meristemalso important inMonocots (esp.grasses)
New Leaves
Shoot apical meristem
The Epidermis
Glandular Trichomes
Dionaea
Drosera
Sarracenia
Basic Leaf Anatomy
Xylem
PhloemBundle sheath
Mesophyll
sub-stomatalchamber
Kranz Anatomy
Leaf c.s. through midrib
Leaf Abscission
Abscissionlayer
Cotyledons
•Mostly storage organs
Heterophylly
• Leaves may be quite different (e.g., in beans, juvenile leaves are entire, while adult leave are compound)
Xerophytes
•Thick cuticle•Sunken stomata•Reduced air spaces in mesophyll (succulent)•Trichomes – boundary layer humid•Multiple epidermal layers
Hydrophytes
•Thin cuticle•Lack characteristics for water conservation•Leaves often lobed (underwater)
Special Features• Bulbs• Tendrils• Plantlets• Insect traps
Kalanchoë
