A leaf is a lateral attachment to the plant stem which supports the main function of photosynthesis. It is an important structure of the plant in charge of feeding.
In Botany, the plants are classified based on various aspects.
Cotyledon is the first significant part of the embryo to emerge from the seed and is formed during the process of embryogenesis along with its roots and shoots before germination. When the seed germinates, cotyledon becomes the embryonic first leaves of a seedling.
Parts of a Leaf
Cotyledons
Considering the number of cotyledons in flowering plants, they can be classified as Monocotyledonous or Monocots (species of plants with single cotyledon or embryonic leaves) and Dicotyledonous or Dicots (species of plant with two cotyledons). Apart from being different in the number of cotyledons, monocots and dicots exhibit various other characteristics of stem, roots, flower parts that distinguish them from each other.
Monocot Leaf
Monocotyledons or Monocots are flowering plants with seeds having a single cotyledon or embryonic leaf. There are about 60000 species of monocots found worldwide.
Monocot leaves are slender and elongated with parallel veins. Compared to other forms of veins, in parallel venation, the veins are small in size with even smaller veins connecting them.
Monocots have flower parts in sets of three. Their roots are fibrous. A few examples of Monocots are Bananas, Palm trees, Grasses, water plantains, Lilies, and Orchids.
Dicot Leaf
Dicotyledons or Dicots are flowering plants with seeds having two cotyledons or embryonic leaves. There are 175000 known species of dicots.
The leaves of a dicot plant have veins distributed in a net-like or reticulated pattern. In such leaves, the veins appear like a finely branched network throughout the leaf blade, with thin veins reticulating between the prominent veins.
The flower parts in Dicots are tetramerous or pentamerous, i.e. in multiples of four or five. Dicots have a tap root system with a long deep primary root growing into finer secondary branches.
Some examples for the Dicots are Oaks, Elms, Maples, Mango, Papaya, Radish, Rose, Castor, and Guava.
Difference Between Monocot and Dicot Leaf
|
Properties |
Monocot Leaf |
Dicot Leaf |
|
Shape |
Usually elongated and narrow |
Dicot leaves are typically broad and round-shaped |
|
Venation |
Monocots have veins parallel to one another |
Dicot leaves have veins that branch out from a single vein like a net |
|
Leaf colour |
The upper and lower surface of a monocot leaf is equally green |
The upper surface of a dicot leaf is usually dark green and the lower surface is light green |
|
Stomata |
Monocot leaves have dumb-bell shaped stomata |
Dicot leaves have kidney bean-shaped stomata |
|
Distribution of Stomata |
Monocot leaf is amphistomatic. Stomata are found in both the upper and lower epidermis |
Dicot leaves are hypostomatic. The stomata are found only on the underside of the leaf |
|
Arrangement of stomata. |
The stomata are arranged in parallel rows and are distributed uniformly on both the surfaces of a leaf. |
In dicot leaves, the stomata are arranged randomly on the epidermis. |
|
Mesophyll |
In Monocot leaves, the mesophyll is single-layered |
Dicot leaves that have two different mesophylls, i.e. Palisade mesophyll and spongy mesophyll. Palisade mesophyll cells are located beneath the leaf’s upper epidermis and Spongy mesophylls are located under the Palisade mesophylls |
|
Motor or Bulliform Cells. |
The bulliform cells are the epidermal cells present in the upper surface of the Monocot leaf. They are large, empty and colourless, and present in the mid-vein region of the leaf |
Motor cells are absent in Dicot leaves |
|
Intercellular spaces |
The intercellular spaces are small due to the compact arrangement of mesophyll cells |
In Dicot leaves, the intercellular spaces are large due to the presence of loosely packed mesophyll cells |
|
Symmetry |
Isobilateral; wherein the surface is the same on both the sides of a leaf because of the presence of a single type of mesophyll cells |
Dorsiventral; in which two surfaces of the leaf differ from each other in appearance and structure because of the presence of two types of mesophyll cells |
|
Vascular Bundles |
There are many small and large-sized Vascular bundles present in a parallel pattern. |
Vascular bundles are generally large in dicot leaves |
|
Protoxylem |
In monocot leaves, the protoxylem elements are distinguishable as protoxylem lacuna |
Dicot leaf (large vascular bundles) do not show differentiation into Protoxylem elements |
|
Bundle Sheath |
Monocot leaves may have a single or double layer of bundle sheath formed of coloured cells due to the presence of chloroplasts |
The bundle sheath of a dicot plant is generally single-layered and is formed of colourless cells |
|
Silica Deposition |
Monocot leaves have a heavy deposition A few examples of Monocots are Bananas, Palm trees, Grasses, water plantains. |
Dicot leaves do not have silica deposition in the walls of epidermal cells. Examples for the Dicots are Oaks, Elms, Maples, Mango, Papaya, Radish, Rose |