Types of Leaves

Depending upon the indentation or incision of lamina, the leaves are of two types:

1. Simple leaf: A simple leaf can be defined as one in which there is a single lamina, and which is not divided completely into distinct leaflets.

1. Pinnate type: When incision take place from margin towards mid-rib.
2. Palmate type: When incision occurs from margin towards base in palmate.

2. Compound leaves (pinnate and palmate): A leaf is called compound when incision of leaf lamina goes down to the mid-rib or to the petiole so the leaf is broken up into number of segments called leaflets.

1. Pinnate compound leaves: In pinnately compound leaf, mid-rib bears laterally a number of leaflets arranged alternately or in opposite manner.
2. Palmate compound leaves: In palmate compound leaf, leaflets are borne at the tip of petiole like the fingers of palm.

phyllotaxy

    Phyllotaxy:

The arrangement of leaves on a stem or branch is called phyllotaxy. Phyllotaxy can be defined as mode of distribution of leaves on stem. Aim of phyllotaxy is to orient the leaves in such a way that they receive maximum sunlight to perform the function of photosynthesis.

It is of two main types:

1. Alternate or Spiral: When there is only one leaf borne at each node, the arrangement is called spiral or alternate. e.g. China, rose.
2. Opposite: In opposite phyllotaxy two leaves appear at each node and lie always opposite to each other.

1. Whorled: When three or more leaves are present at node, phyllotaxy is known as whorled.

Characters distinguishing simple and compound leaf

 

Difference between simple and compound leaf:

Characters	Simple leaf	Compound leaf
1. Incision	The lamina is not divided into distinct lobes or leaflets i.e. it has single lamina.	The lamina is incised into or more distinct leaflets.
2. Arrangement	Simple leaves appear in acropetal succession on stem.	Leaflets of a compound leaf do not appear in acropetal succession on rachis.

      

Characterstics distinguishing pinnate  and palmate compound leaf

Differences between pinnate compound leaf and palmate compound leaf:

Characters	Pinnate compound leaf	Palmate compound leaf
1. Shape	Feather like.	Like palm of hand.
2. Origin of leaflets	Leaflets appear on elongated axis.	Leaflets appear from common point.
3. Appearance	Leaflets appear in two rows.	Leaflets are clustered together.
4. Stipules	Its axis.	Joint is usually present between leaflet and point of attachment.
5. Origin	Axis bearing leaflets is continuation of branch of mid-rib.	Tip of petiole represents the leaflet bearing point.