Cortex - Plant Tissue

The tissue of unspecialized cells in plants is called the cortex, it lies between the epidermis(surface cells) and the vascular or conducting tissues of roots and stems. Whereas, cortical cells may contain stored carbohydrates or other substances like resins, latex, essential oils, and tannins.

In some roots along with herbaceous stems rarely in woody stems, the cortical cells in the innermost layer are differentiated into a cell layer called the endodermis. The Casparian strip or plant structure is found in the endodermis. It has woody cell walls and a corky band found around all the cell walls with the exception of those facing toward the axis and therefore the surface of the base or stem or root. 

The endodermis with its Casparian strips may operate in regulating the flow of water between outer issues and therefore the vascular cylinder at the centre of the root. Some flowering plants have a starch sheath (a layer of cells with stored starch) within one inch or two inches of shoot tips which lies in the same position as an endodermis.

Anatomy of a Plant Stem

Given below is the cross section of a flax plant stem:

• Pith

• Protoxylem

• Xylem l

• Phloem l

• Sclerenchyma (bast fibre)

• Cortex

• Epidermis

Anatomy of Cortex Plant Tissue

The cortex consists of large thin-walled parenchyma cells of the bottom tissue system while showing little to no structural differentiation. The outer cortical cells often obtained unevenly thickened cell walls, called collenchymas cells. A number of the cortical cells could also contain chloroplasts. The cortex sorts of layers of the cells that constitute cork. It is liable for the transportation of the materials into the central cylinder of the basis through diffusion and is also used for food storage within the sort of starch. The endodermis is the innermost layer of the cortex.

In the case of a lichen, the cortex is the “skin”, or outer layer of thallus tissue that covers the undifferentiated cells of the medulla. In Fruticose lichens one cortex encircles the branches, it may be either flattened or have leaf-like forms; foliose lichens have different upper and lower cortices; crustose, placodioid, and squamulose lichens have upper cortex but lacks the lower cortex; while leprose lichens are devoid of the cortex.

Pith

Pith, or medulla, is that tissue in the stems of the vascular plants. Pith consists of spongy and soft parenchyma cells, which store as well as transport nutrients throughout the plant. Pith is found within the centre of the stem in eudicotyledons. In monocotyledons, it also extends into flowering stems and therefore the roots. The pith is encircled by a ring of xylem; the xylem is encircled by a ring of phloem.

What is Phloem?

The living tissue in vascular plants called phloem transports the soluble organic compounds which are manufactured during photosynthesis. Specifically the sugar sucrose, to different parts of the plant where it is needed. This transport process is noted as translocation. The phloem is derived from the Greek word floiós which means "bark" inside the tree, as the name suggests it is the innermost layer. Carl Nageli was the one who coined the term in 1858.

Phloem and Companion Cells

• Xylem

• Phloem

• Cambium

• Pith

• Companion cells

There are Two Sorts of Companion Cells:

1. Ordinary companion cells are those which have smooth walls and few or no plasmodesmatal connections to the cells aside from the sieve tube.

2. Transfer cells are those which have much-folded walls that are adjacent to non-sieve cells, allowing larger areas of transfer. Transfer cells specialized in scavenging the solutes from those during which the cell walls that are actively pumped require energy.

Is Cortex a Primary Tissue?

The mass of primary tissue in stems as well as roots extends inward from the epidermis to the phloem. The cortex may be composed of only one or a mixture of all the three major tissues: collenchymas, parenchyma along with sclerenchyma.

The cortex makes up a substantial proportion of the quantity within the root, particularly within the young roots, where it operates within the transport of water and therefore the ions from the epidermis to xylem and phloem or vascular tissues. In the older roots, it operates primarily as a storage tissue.

Is Cortex a Ground Tissue?

The cortex rests between the hypodermis and ground tissue, together with several layers of parenchyma cells. The bottom tissue is additionally composed of the parenchyma cells and therefore the vascular system.

Cortex and Pith

The cortex is found to the surface and/or round the vascular bundles, while the pith is found within the centre of the stem. Parenchyma cells are the main components of both the cortex and pith. Unlike dicots, monocots usually don’t have an outlined cortex and pith.

Functions of Cortex and Pith

In most plants, Pith and Cortex cells operate to support.