Flowering plants are divided into monocots (or monocotyledons) and dicots (or dicotyledons). This comparison examines the morphological differences in the leaves, stems, flowers and fruits of monocots and dicots.
|Embryo||As the name suggests, the dicot embryo has two cotyledons.||Monocotyledons have one cotyledon in the embryo.|
|Leaf venation||Leaf veins are reticulated (branched).||Leaf veins are parallel.|
|Type of leaves||Dorsiventral||Isobilateral|
|Stomata in leaves||Some dicots are epistomatous i.e., they have stomata only on one surface on their leaves.||Monocots are amphistomatous i.e., monocot leaves have stomata on both the upper and lower surface.|
|Bulliform cells||Dicot leaves do not have bulliform cells.||Many monocots have bulliform cells on their leaves to regulate the loss of water.|
|Flowers||Petals in multiples of four or five. May bear fruit ( if tree).||Petals in multiples of three.|
|Root Pattern||Taproot system||Fibrous roots|
|Secondary growth||Often present||Absent|
|Stem and vascular system||Bundles of vascular tissue arranged in a ring. The vascular system is divided into a cortex and stele.||Bundles of vascular tissue scattered throughout the stem with no particular arrangement, and has no cortex.|
|Pollen||Pollen with three furrows or pores.||Pollen with a single furrow or pore.|
|Presence or absence of wood||Both herbaceous and woody||Herbaceous|
|# of seed leaves||2 seed leaves||1 seed leaf|
|Examples||Legumes (pea, beans, lentils, peanuts) daisies, mint, lettuce, tomato and oak are examples of dicots.||Grains, (wheat, corn, rice, millet) lilies, daffodils, sugarcane, banana, palm, ginger, onions, bamboo, sugar, cone, palm tree, banana tree, and grass are examples of plants that are monocots.|
History of the Classification
The classification of flowering plants or angiosperms into two major groups was first published by John Ray in 1682, and later by the botanist Antoine Laurent de Jussieu in 1789, replacing the earlier classifications. According to this classification, flowering plants were divided onto eight major groups, the largest number of species belonging to monocots and dicots.
Seed Coats around embryo
The number of cotyledons differs in the two types of flowering plants, and forms the basis for the main classification of monocots and dicots. Cotyledons are the seed leaves of the embryo and contain nutrition for the embryo until it is able to grow leaves and produce food by the process of photosynthesis. Monocots have only one cotyledon while dicots have two.
Dicot vs Monocot Stem
The vascular system in dicots is divided into a cortex and stele but in monocots these distinct regions are absent.
The vascular system is scattered in monocots, with no particular arrangement. But if you take a look at the cross section of the stalk in dicots you will find the vascular bundles consist of primary bundles forming a cylinder in the centre.
The number of flower parts is different in the two groups. They occur in multiples of three in monocots and in multiples of four or five in dicots.
Differences in Monocot and Dicot Leaves
Dicot leaves are dorsiventral i.e., they have two surfaces (upper and lower surface of the leaf) that differ from each other in appearance and structure. Monocot leaves are isobilateral i.e., both surfaces look the same and are structurally the same and are both exposed to the sun (usually vertically oriented).
Leaf veins are arranged either in parallel through the length of the leaf or in a reticulate arrangement throughout the leaf. In most species, monocot leaves have parallel arrangement while dicots have reticulate venation of leaves.
Monocot leaves have stomata on both their surfaces, but some dicots have stomata on only one surface (usually the lower one) of their leaves. Moreover stomata in monocot leaves are arranged in highly ordered rows, whereas the dicots have more of a crazy-paving of them.
Stomata are bordered by a pair of specialized guard cells that regulate the size of the stomatal opening. Monocots and dicots differ in the design of the guard cells; they are dumbbell-shaped in monocots and look like a pair of sausages in dicots.
Bulliform cells help regulate water loss. They are present on the upper surface of the leaves in some monocots. When water supply is abundant, bulliform cells become turgid and consequently the leaf straightens up, which exposes the leaf and leads to evaporation of excess water. Conversely when water is in short supply, bulliform cells shrink and the leaf curls in and becomes less susceptible to water loss through exposure.
Dicots do not have bulliform cells in their leaves.
There is also a different type of pollen structure present in the two classes. Monocots developed from plants with a single pore or furrow in the pollen, whereas dicots developed from plants with three furrows in their pollen structure.
Roots can develop either from a main radicle or arise in clusters from the nodes in the stem, called adventitious roots. Monocots are known to have adventitious roots whereas dicots have a radicle from which a root develops. A fibrous root system, with several moderately branching roots growing from the stem, is common in monocotyledons. In contrast, dicots have a taproot system, a tapering root that grows downward and has other roots sprouting laterally from it.
Secondary growth is found in dicots but absent in monocots. Secondary growth helps in the production of wood and bark in trees.
Examples of Monocots and Dicots
There are about 65,000 species of monocots. Some examples include lilies, daffodils, grains, sugarcane, banana, palm, ginger, rice, coconut, corn and onions.
There are about 250,000 species of dicots. Examples include daisies, mint, pea, tamarind, and mango.
There are some exceptions to this classification. Some species belonging to monocots can have characters belonging to dicots, since the two groups have a shared ancestry.