A Study on Typical Dicot Leaf

Introduction

Although there are exceptions, most dicots have floral parts (sepals, petals, stamens, and pistils) that are based on a plan of four or five, or multiples thereof. 

The majority of the leaves are net-veined, which means the vessels that transport water and food have a mesh like structure. 

The vessels in the stems are frequently arranged in a continuous ring at the surface of the stem. 

About half of all dicot species are woody, with an annual increase in stem diameter due to the development of new tissue by the cambium, a layer of cells that continues to divide throughout the life of the plant.

Taproots and stem branching are both prevalent.

Dicot leaf structure

Dicot leaves are not as linear as monocot leaves, and their vascular structures take the form of net-like veins rather than parallel ones. 

The appearance of this reticulate venation pattern is usually one of two types. A pinnate leaf (similar to a feather) has a central vein that runs down the centre of the leaf, with additional veins branching off to either side. 

Veins branch out from a single point on a palmate pattern leaf to generate a shape that resembles the palm of a hand.

Dicot leaves typically feature more stomata on the lower side of the leaf or just stomata on the lower side of the leaf. Hypostomatous leaves are those that only have stomata on the lower side.

Palisade mesophyll and spongy mesophyll are two forms of mesophyll found in dicot leaves (and a few uncommon, “net-veined” monocot leaves).

 Palisade mesophyll cells are found beneath the upper epidermis of the leaf. They have the maximum amount of chloroplasts of any plant cell, making them ideal for photosynthesis. 

Below the palisade mesophyll lies the spongy mesophyll. Its cells, which likewise include a lot of chloroplasts, are spaced widely apart than the palisade mesophyll cells. 

Because spongy mesophyll is loosely packed, gases can travel more easily through the leaf tissue.

Dicot root 

Dicot roots have a taproot structure, which means they develop into the soil as a single thick root with lateral branches. Dicot roots’ primary vascular structures are surrounded by ground tissue, which is mostly made up of parenchyma cells.

Phloem

In vascular plants, the xylem and phloem form continuous tubes that carry water, nutrients, and other substances throughout the plant’s roots, stem, and leaves. 

Positive hydrostatic pressure in the phloem moves dissolved sugars and organic compounds from the leaves downward to the stem and roots via a process called translocation. 

The phloem of monocots and dicots contains conducting cells (sieve elements) and companion cells. Conducting cells have thin walls, and they are alive in the mature plant, but they lack a nucleus and most other organelles.

Dicot phloem also contains phloem parenchyma, fibres, and sclereids.

Stele

The stele (or vascular cylinder) is located in the root’s core area, where the xylem and phloem grow. 

The stele of dicot roots has phloem clusters clustered around the primary xylem. 

Dicot steles have an extra component termed cambium that isn’t found in monocot roots. Pith is absent from dicot root steles.

Pericycle

The pericycle is the stele’s outermost layer (or vascular cylinder). Because it is formed by the procambium, it is believed to be part of the vascular cylinder, despite being made up of nonvascular parenchyma or sclerenchyma cells.

The pericycle helps the root grow by supporting it, protecting its vascular structures, storing nutrients, and facilitating root growth.

In both monocots and dicots, pericycle cells can divide and produce lateral roots. The pericycle also produces meristem cells, which stimulate secondary root growth, as well as the cambium, which creates xylem and phloem in dicots.

Dicot stems

Ground tissue, which mostly comprises parenchyma cells, makes up the majority of the dicot stem. 

Sclerenchyma and collenchyma cells can also be seen in areas where extra strength is required.

 A ring of vascular bundles, made up of xylem and phloem, divides the ground tissue into the outer cortex and interior pith in dicot stems. 

Cambium is a component found in dicot vascular bundles that is not seen in monocot stems.

Epidermis

The epidermis is a single layer of cells that protects the stem’s outer dermal tissue layer from harm due by sunlight, infections, and herbivores. 

Multicellular trichomes (hairs) protrude from the epidermis of dicot stems. The epidermis of woody dicot stems is replaced by periderm, which is made up of cork and other tissues. 

Dermal cells in certain stems exude a waxy material that creates a cuticle, a protective covering that aids in water retention.

Conclusion

About half of all dicot species are woody, with an annual increase in stem diameter due to the development of new tissue by the cambium, a layer of cells that continues to divide throughout the life of the plant.

Although there are exceptions, most dicots have floral parts (sepals, petals, stamens, and pistils) that are based on a plan of four or five, or multiples thereof.

Dicots are estimated to number over 175,000 species. 

Dicots include the majority of garden plants, shrubs and trees, as well as broad-leaved blooming plants like magnolias, roses, geraniums, and hollyhocks.