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The Cortex in Vascular Plants

Bridget Curran, Laura Nappi
  • Author
    Bridget Curran

    Bridget is completing her M.S degree in Biology at Plymouth State University and received a B.S degree in Biology with a minor in Chemistry from Castleton University. She has experience teaching biology and botany for three years at Plymouth State University.

  • Instructor
    Laura Nappi
Learn about the cortex in plants, and understand its function. Explore other layers of the plant stem and discover the location of pith in plants. Updated: 02/02/2022

Table of Contents


Cortex in Plants

The stem in vascular plants holds the roots, leaves, and reproductive structures. The stem is essential for the support, protection, and transportation of water and nutrients to the entire plant. The stem in vascular plants consists of three types of tissues: dermal, vascular, and ground tissue. A tissue is a group of cells that have a common structure or function. The main focus of this lesson is the cortex of plants, which is a ground tissue and lies between the epidermis (dermal tissue) and vascular tissue. The main function of the cortex is to provide support and perform metabolic processes. The specific function of the cortex is dependent on the type of cells present. This lesson will discuss vascular plant stem anatomy, the role of the cortex, and how it functions in vascular plants.

Layers of the stem at 100x magnification

Stem layers at 100x magnification

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  • 0:00 Layers Of A Plant Stem
  • 1:27 What Is The Cortex?
  • 1:49 Function Of The Cortex
  • 2:44 Lesson Summary
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Cortex Function in Plants

The function of the cortex is dependent on the type of cells present. The cortex is part of the ground tissue in vascular plants. The ground tissue is made up of three simple cell types: parenchyma, collenchyma, and sclerenchyma.

  1. Parenchyma cells: function in metabolism and wound healing
  2. Collenchyma cells: function in support
  3. Sclerenchyma cells: function in support and protection

The structures and shapes of each cell type are morphologically different and are located in different parts of the stem in order to perform specific functions.


Parenchyma cells make up the majority of ground tissue. They have thin cell walls and occur as a mass in the stems and roots of plants. They are alive at maturity, meaning they are actively dividing. This is important for wound healing and plant growth. The function of parenchyma cells is largely metabolic. They are important in photosynthesis and the transport and storage of nutrients.


Collenchyma cells are usually located just under the dermal tissue of stems and leaves and are essential in mechanical support. The cell walls of collenchyma cells are thicker than that of parenchyma cells, so they are able to stretch as the plant grows.


Sclerenchyma cells are essential to the structural support of plants. Unlike collenchyma and parenchyma cells, sclerenchyma cells are dead at maturity and have the thickest cell walls of the three. There are two forms of sclerenchyma cells: fibers and sclereids. Fibers are often long strands or bundles and are essential to support the plant. Sclereids are much thicker cells that can vary in shape depending on the function and type of plant they occur in. They are the primary structural support as they are the most rigid of the cell types. These are common in plants such as legumes, which have a thick outer seed pod covering. In addition to structural support, these cells offer some protection towards herbivory, which is the consumption of plants by animals.

Other Layers of the Plant Stem

As mentioned in the first section, the plant stem has three distinct tissues or layers: ground, dermal, and vascular.

  • Dermal tissue: The outermost layer of the plant. Its primary role for the plant is gas exchange and protection to internal structures.
  • Ground tissue: The supportive tissue in between the dermal and vascular tissue.
  • Vascular tissue: Consists of xylem and phloem. Its primary function is to transport water and nutrients from the roots to the rest of the plant.


The dermal layer is the outermost layer of the plant and consists of a single layer of cells called the epidermis. The function of the epidermis is to protect the internal structures of the plant, retain water, and exchange gasses. Leaf epidermis contains openings called stomata or singular stoma. The stoma has two guard cells on either side that open and close in response to light and precipitation to allow gas exchange. They will open to take in carbon dioxide and release oxygen and water (photosynthesis). Another type of cell present on the epidermis are trichomes. Trichomes are appendages that grow from epidermal cells. They protect the plant from UV radiation and herbivory. The morphology and number of trichomes occurring on any given plant vary between plant species, environmental stressors, and the presence of herbivores.

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Frequently Asked Questions

What is the main function of the cortex and pith?

The main function of the cortex and the pith is to transport and store nutrients and provide support. The cortex is located between the epidermis and the vascular tissue while the pith is located in the center of the stem, after the vascular bundles.

What is the function of the cortex cell?

The function of the cortex cell is dependent on the type of cell. Parenchyma cells have metabolic functions in photosynthesis, transporting and storing nutrients, and wound healing. Collenchyma cells provide structure to the plant and are able to stretch as the plant grows. Sclerenchyma cells have much thicker cell walls and are essential for structural support, and in some cases protect against herbivory.

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