1. Parts of typical leaf
1.Leaf base 2.Petiole 3.leaf lamina
• It is the stalk that connects a leaf to
the stem of the plant
• It is the lowermost part of a
leaf attaches the leaf to the stem
• It is the thin, flat part of the leaf
that is typically green in color.
• It divided into three parts:
i) leaf apex
ii) leaf margin
iii)veins
Margin
Apex
Veins
Pulvinus leaf base in mango
Sheathing leaf base in
petiole
Sessile leaf-rice, grass
Petiolate leaf-rose ,hibiscus, mango etc
2. Leaf types
1.Simple leaf 2.Compound leaf
e.G Guava ,hibiscus
Palmately compound Pinnately compound
e.g.silk cotton, oxalis,
Aegle marmelos
e.g. Neem , cassia ,fistula,
rose
3. Phyllotaxy
Opposite decussate
1.Alternate phyllotaxy Opposite superposed 3.Whorled phyllotaxy
2.Opposite phyllotaxy
e.g. hibiscus ,
mango, cotton,
Sunfiower.
e.g. calatropis, zinnia,
Tulsi.
e.g. Quisqualis, guava
, jamun.
e.g. Nerium ,alstonia
Defination – The arrangement of leaf on the stem by petiole is known as phyllotaxy.
4. Venation in leaf
Defination – The arrangement of veins & veinlets in lamina of the leaf.
There are of two types- 1)Reticulate venation 2)Parallel venation
1) Reticulate venation- The veins & veinlets are irregularly distributed in leaf lamina.
Reticulate venation is common found in dicotyledons.
There are of two types – i) reticulate unicostate ii) reticulate multicostate
a)Reticulate Multicostate convergent b)reticulate Multicostate divergent
2) Parallel venation- The veins run parallel to each other in leaf lamina.
Parallel venation is commonly found in monocotyledons.
There are of two types- i) parallel unicostate ii) parallel multicostate
a) Parallel Multicostate convergent b) Parallel Multicostate divergent
5. Reticulate venation -
1) Reticulate unicostate 2) reticulate multicostate convergent 3)reticulate multicostate divergent
e.g. pipal mango banyan e.g. ziziphus e.g. castor
6. Parallel venation-
Parallel unicostate venation
e.g. banana
Parallel multicostate convergent
e.g. maize, bamboo , eichornia
Parallel multicostate divergent
e.g. fan palm
7. Modification of leaf
• leaves are specialised to perform photosynthesis.
• It play some imp role, such as support, storage of food, defence etc.
They have been modified into different forms.
1.Leaf Spines –opuntia, agave, argemone
2.Leaf tendrils – wild pea, pisum sativum (pea), gloriosa
3.Storage Leaves – xerophytic plants
4.Scale Leaves – casuarina, asperagus
5.Leaf Roots - salvinia
6.Leaflet Hooks - bignonia unguiscati.
7.Phyllode - Australian Acacia.
8.Insectivorous Leaves
a)Leaf Pitcher - nepenthes
c)In Drosera – venus fiy trap
b)Leaf Bladder - utricularia
