What is a Dicot Leaf?

If the plant is a dicotyledon, its leaves have unique characteristics. Externally, for example, unlike the leaves of monocotyledonous plants, there are midribs and have veins which would be different and would be on the leaf’s surface.

Structure of Dicot Leaf

Upper epidermis

The layer which would be present outside resides on the leaves. This is a monolayer of parenchymal cells with no intercellular space. The outer wall of the cell is would be having a layer, which is known as a cuticle, and it is protective in nature.  This would have pores which are small in nature.

Lower epidermis

The layer present outside that lies beneath the leaves. This is a monolayer of parenchymal cells with no intercellular space. The outer wall of the cell is covered with a thin cuticle. There are quite a few pores in this layer. Chloroplasts are found only in bean-shaped guard cells surrounding the openings of the stomata. Pore, with the help of the lower epidermis;

• Useful for gas exchange.
• Promotes the loss of water vapor due to the transpiration process.  

Between the upper and lower epidermis is a mass of ground tissue called mesophyll. It consists of two different types of substance – Palisade Mesophyll and Spongy Mesophyll.

•  Palisade Mesophyll-This substance lies below the upper part of the epidermis. These are elongated parenchymal cells because they have more chloroplasts. Therefore, these cells are involved in the process of photosynthesis. Cells have very narrow intercellular spaces. 
• Spongeous Mesophyll-The spongy parenchymal lies beneath the palisade parenchymal tissue. Here, the tissues are irregularly arranged in the intercellular spaces. As a result, the shape of the cell is almost spherical or oval. This organization is also useful for gas exchange.  

Vascular Bundle

Vascular bundles occur in the midribs and veins. Each vascular bundle is composed of xylem and phloem and is surrounded by a cell envelope consisting of a parenchymal called the bundle envelope. The vascular bundles are connected and collaterally closed, with the xylem facing the upper layer of the epidermis and the phloem facing the lower layer of the epidermis.

Cuticle

The cuticle, which can vary in thickness, covers the epidermis’ outer walls. It might have more wax layers. The Upper and lower epidermis are fully lined with parenchymatous cells. Although there is only one layer, young plants have stratified epidermis. Ficus elastica, for instance. Hairs in the epidermis can be glandular or non-glandular. 

Stomata

Stomata are more prevalent in the lower epidermis than the upper epidermis. The presence of stomata in the upper epidermis is established in some free-floating hydrophytes, though. Stomata in xerophytes are buried or borne in pits. Nerium is an example.

Mesophyll

The mesophyll is composed of spongy parenchymal and palisade parenchymal.  Parenchymal which is palisade and also the chloroplast are located near the lower surface, while palisade parenchymal is located toward the higher surface. Sclereids of various types are also present in the mesophyll. An illustration would be the osteosclerosis, or rod-shaped stone cells, found between palisades on Hakea leaves. Some hydrophytes have sphaeraphides in their specialisation cells or sclereids which would be branched and their vast air spaces (Nymphaea). For instance, in Trapa bispinosa, the vascular bundles in the mid-rib are conjoint and collateral. While the xylem is located on the top side, the phloem is located on the lower side. There is only one vascular bundle in Nerium, Cannabis, Prunus, and other plants. Bulliform cells aren’t found in dicot leaves, although sunflower vitis and other plants have numerous vascular bundles.

Differences between the dicot and monocot leaf 

Shape-Monocot would have larger and thin leaves but in the case of dicot we would see wide and small leaves

Stomata-Dicot would be in the shape of a kidney and monocot would be in the shape of dumbell.

Stomatal arrangement-In monocot stomata would be present in the up and lower and in dicot stomata would be present only downside.

Vascular bundles-In monocot they would be small and dicot they would be larger.

Color-Monocot leaves do not show difference in colour as whole leaves exhibit the same color whereas dicot leaves show color differentiation.

Venation-Monocot exhibit parallels whereas in dicot we would see reticulated.

Extension of bundle sheath-In dicot it would be parenchymatous and in monocot it would be sclerenchymatous.

Space-In monocot spaces between cells is tighter as well as in dicot spaces would be larger.

Characteristics of Dicot Leaf 

• It has wider and short leaves
• Exhibit  reticulate venation
• Intercellular spaces which are present would be large
• Bundle sheathing would be parenchymatous.
• The Colour would be different in upper and lower as dark and light green.
• Vascular bundles which would be present are large.
• Orientation would be in the form of dorsiventral.
• Stomata would be in the shape of the kidney.

Conceptual Question

Question 1: Venation type of dicot leaf? 

Answer:

It would exhibit the venation which would be parallel.

Question 2: Shape of the stomata in the dicot leaf?

Answer:

It would exhibit shape in the form of the kidney.

Question 3: Outer part of the dicot leaf?

Answer:

The upper epidermis would be present outside and this would have pores.

Question 4: What Bundle sheath in the dicot leaf would be?

Answer:

Bundle sheath would be of parenchymatous.

Question 5: Vascular bundles in the dicot leaf?

Answer:

Vascular bundles present in the dicot leaf would be large in size.

Question 6: The outer wall of dicot leaf?

Answer:

It would be called a cuticle which would help in protection.