True seeds (Angiosperms) are produced by some plants, but true seeds are not produced by others (Gymnosperms). These two flowering plants are distinguished by the number of cotyledons. In the case of root, stem, and leaves, dicotyledonous and monocotyledonous plants have different anatomy. Continue reading to learn more about dicotyledonous plant anatomy.

Angiosperms are flowering plants that are classified into two groups based on how many cotyledons they have. Plants that are monocotyledonous and dicotyledonous. Dicotyledonous plants are those that have two cotyledons, such as sunflowers and mangoes.

Dicotyledons

Flowering plants (angiosperms) are divided into two groups: dicotyledons. Monocots and dicots are the two types of flowering plants that are usually classified. The members of each group have a lot in common.

Dicots are named from the number of cotyledons, or embryonic leaves, found in the seed embryo—two (di-) cotyledons are found in the seed embryo. Dicots, unlike monocots, are not a monophyletic group, which means that their evolutionary history cannot be traced back to a single most recent common ancestor. Rather than the monocots, a number of lineages split first.

Remember that there are always exceptions to the rule when classifying flowers as monocots or dicots. Early-diverging dicots feature scattered vascular bundles, trimerous flowers, and monosulcate pollen grains, which are typical monocot traits. Approximately 2% of flowering plants do not fall into either category.  

Dicotyledonous Root

• The topmost layer is Epiblema. Epiblema cells frequently emerge in the form of unicellular root hairs.
• Many layers of parenchyma cells with thin walls and intercellular spaces make up the cortex.
• Endodermis is the lowest layer of the cortex, consisting of a single layer of barrel-shaped cells with no intercellular gaps.
• Suberin, a water-impermeable waxy material, is deposited in the form of Casparian strips on the tangential and radial walls of endodermal cells.
• The pericycle is a layer of parenchymatous cells with thick walls that lie adjacent to the endodermis.
• These cells initiate the production of lateral roots and vascular cambium during secondary growth. The pith is inconspicuous and unnoticed.

Dicotyledonous Stem

As depicted in the transverse section of a typical young dicotyledonous stem, the epidermis is the stem’s outermost protective layer.

• It is covered in a thin layer of cuticle and may feature trichomes and a few stomata.
• Between the epidermis and the pericycle, the cortex is made up of cells arranged in numerous layers.
• It’s split into three sections.
• The outer hypodermis, which lies just beneath the epidermis, is made up of a few layers of collenchymatous cells that provide mechanical support to the embryonic stem.

The cortical layers underneath the hypodermis are made up of round thin-walled parenchymatous cells with obvious intercellular gaps. The endodermis is the brain’s lowest layer.

The layer is also known as the starch sheath because the endodermis cells are tightly packed with starch granules. On the inner side of the endodermis and above the phloem, the pericycle occurs as semilunar patches of sclerenchyma. Between the vascular bundles are the medullary rays, which are a few layers of radially placed parenchymatous cells.

Dicot stems are notable for their ‘ring’ configuration of vascular bundles, which is made up of a large number of them. Each vascular bundle is connected, open, and terminates in a protoxylem.

Dorsiventral (Dicotyledonous) Leaf

The epidermis, mesophyll, and vascular system are visible through the lamina in a vertical section of a dorsiventral leaf. The leaf’s epidermis has a conspicuous cuticle that covers both the upper (adaxial epidermis) and lower (adaxial epidermis) surfaces (abaxial epidermis). The abaxial epidermis, on average, has more stomata than the adaxial epidermis. In the latter, stomata may even be non-existent.

• The tissue that sits between the top and bottom epidermis is known as mesophyll. Parenchyma, which includes chloroplasts and performs photosynthesis, makes up the mesophyll.
• This tissue is made up of two types of cells: palisade parenchyma and spongy parenchyma. 

Characteristics of Dicot Seed

• The seed coat is the dicot seed’s outermost coating. 
• Helium is a scar on the seed coat that was used to bind the developing seeds to the fruit.
• The micropyle is a tiny pore located near the helium.
• The embryo, which consists of an embryonic axis and two cotyledons, is contained within the seed coat. The cotyledons are usually plump and rich in food reserves.
• Endospermic tissue is found in some seeds and stores food for the embryo. Castor, cotton, and coffee are examples of endospermic seeds.
• Non-endospermic seeds, such as bean, gram, and pea, lack a food reserve.

Examples of Dicot

Oak Trees

Despite the fact that we don’t think of these trees as flowering plants, they do have small, inconspicuous blooms. Since they are little and yellow-green, these flowers are sometimes overlooked because they mix in with their environment.

The existence of wood and bark as a result of secondary growth—a trait not found in monocots—is perhaps a clearer indicator that the oak tree is a dicot.

Daisies

Daisy is an herbaceous plant that does not produce secondary growth. Secondary growth is usually a telltale sign of a dicot, but the daisy’s lack of it does not rule it out as a dicot; in fact, only approximately half of dicot species are woody. There are other traits to check for instead of the presence or lack of secondary growth to establish whether the daisy is a dicot. When you count all the petals on a daisy, you’ll notice that the floral parts are in multiples of four or five, which is typical of a dicot. The daisy’s leaves also have veins that branch out in a net-like, or reticulated, pattern, indicating that it is a dicot.

Conclusion

On a dicot, the total number of floral parts is divisible by four or five. Geraniums are a type of dicot. Dicot seeds develop two seed leaves as they germinate. Small veins expand outwardly from the larger veins in mature dicot leaves, resulting in a dense network of veins. A dicot leaf’s vein system has an uneven, web-like appearance. 

The majority of trees have clear examples of dicot leaves growing on them. A dicot stem’s vascular system is well-organized. The vascular tissue is structured into a series of concentric circles that give the stem its cylindrical shape. Dicots, unlike monocots, can typically produce a layer of bark to protect themselves. Pollen grains from dicots have three pores or furrows.