Simple and Compound Leaves





Considering the way the leaf blade or lamina, the leaves are divided into simple and compound leaves. The upcoming discussion will give you a clear idea so that it will very easy to understand about the difference between the Simple and Compound Leaves.

Simple leaves

A simple leaf consists of a single, entire or dissected lamina. The simple leaf has got all the structures of a typical leaf i.e., leaf blade, leaf apex, leaf-base, leaf margin.




The dissection or incision of a leaf depends on the type of venation. In pinnately compound leaves, the incision progresses from the leaf margin to the midrib, but in palmately compound leaves, the incision progresses from the margin to the base of the leaves. To understand the difference between the simple and compound leaves let us know the incisions which are named as follows:

Simple leaves

1) When the incision reaches less than half-way down the margin, it is described with a suffix.
2) If the opening reaches less than half-way down the margin, it is described with a suffix-partite.
3) When the incision roughly reaches the midrib, it has a suffix-sect. According to the pinnate and palmate type of venation of incised leaves they are:
i) Pinnatifid. e.g. poppy
ii) Palmatifid. e.g. cotton,
iii) Pinnatipartite. e.g. Brassica.
iv) Palmatipartite. e.g. castor
v) Pinnatisect. e.g. Tagetis
vi) Palmatisect. e.g. silk-cotton.
vii) Lyrate : The pinnately compound leaves show irregular incision having larger lobes towards the apex and smaller lobes towards the base. e.g. Brassica (mustard).
viii) Pedate : The lobes of palmately incised leaves are arranged like the claws of a bird and called pedate leaves e.g. Vitis.




Compound Leaf

A leaf is said to be compound, when the leaf blade is dissected into a number of small segments called leaflets. The disconnected segments of a compound leaf are called leaflets, which are arranged on the axis or midrib or rachis, the leaflets are either arranged imaginatively on both side of rachis in pinnately compound leaves or the leaflets may be borne terminally on the rachis impalmately compound leaves. So from our above discussion it is quite clear about the difference of simple and compound leaves.




Types of compound leaves

The compound leaves are of two main types, those are:
1) Pinnately compound leaves
2) Palmately compound leaves

Pinnately compound leaf

Pinnately compound leaf originates from a pinnatisect leaf, when the incision touches the midrib. The midrib is transformed to form the rachis, while the lobes form the individual leaflets, which remain arranged along the two sides of the rachis in the form of the following types :

Unipinnate
Compound Leaves

The leaflets are borne directly by the rachis and on the basis of the number of leaflets they can be classified into two types, those are:
i) Paripinnarte : The leaflets are arranged in pairs on opposite side of the rachis, the leaf contains even number of leaflets and the rachis shows indeterminate growth, e.g. tamarind, Saraca.
ii) Imparipinnate : The growth of the rachis is determined by an apical leaflet, so there are always odd number of leaflets, e.g. rose.

Bipinnate

The rachis produces the secondary branches in pinnate fashion, which bear the leaflets called pinnules arranged in pinnate fashion e.g. Mimosa pudica.




Tripinnate

In this type of leaf, the rachis produces the secondary and tertiary branches, which ultimately produces the pinnately arranged leaflets, e.g. Moringa (B. Sajina).

Decompound

The leaves in fact appear to be more than tripinnate, but actually it is finely pinnatisect and is called decompound e.g. carrot, coriander.

Palmately compound leaf

The palmately compound leaf arises from a palmaticsect leaf where the opening reaches the base of the lamina. They are so called because the leaflets arise from the tip of the shortened rachis in the form of digits of a palm. On the basis of the number of leaflets the palmately compound leaf may be classified as (i) Unifoliate (ii) Bifoliate (iii) Trifolitate (iv) Quadrifoliate and (v) Multifoliate.
So, a clear idea about the simple and compound leaves we have obtained from our above discussion.



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