The internal organization of plants is structured into different tissue systems that together form the primary and secondary body of the plant. These tissue systems play crucial roles in supporting the plant's functions, growth, and development. There are three primary tissue systems: dermal, ground, and vascular, and they collectively make up the primary plant body. In some woody plants, secondary growth adds a secondary vascular tissue system.


**1. Dermal Tissue System:**

   - **Function:** 

The dermal tissue system is the outermost protective covering of the plant. It functions as a barrier against physical damage, pathogens, and excessive water loss.

   - **Components:**

 It consists primarily of the epidermis, which may have specialized structures like stomata (for gas exchange) and trichomes (hair-like structures).

   - **Location:**

The dermal tissue system covers the entire plant's surface.

**2. Ground Tissue System:**

   - **Function:** 

The ground tissue system carries out various functions, including photosynthesis, storage of nutrients, and providing structural support.

   - **Components:**

 It comprises three types of ground tissue:

     - **Parenchyma:**

 These cells are involved in photosynthesis, storage, and gas exchange.

     - **Collenchyma:** 

Collenchyma cells provide mechanical support to growing parts of the plant.

     - **Sclerenchyma:** Sclerenchyma cells, such as fibers and sclereids, provide rigidity and strength to non-growing tissues.

height="506" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFdfgc-Yv-55nEdq6-LYT2BMevEspirjPWREGMSrNwdylaD2UltoBX57ZS06QMhvgBiUa2m0lWkwNyq7x05B8rlNt-IZxEW1h4DGm3xN8AslUoenYhBRSz706rTumoF2ocXP3uvp5KTpVteEmUQyRz5Asfj8_N1Mv2xCz7z8LGxFiQNeHiQE24NIhYom4/w640-h506/image-4.png" width="640" />


**3. Vascular Tissue System:**

   - **Function:** 

The vascular tissue system is responsible for the long-distance transport of water, nutrients, and food throughout the plant. It also provides structural support.

   - **Components:** 

It comprises two main types of vascular tissues:

     - **Xylem:** 

Xylem is responsible for transporting water and minerals from the roots to the rest of the plant. It consists of vessels, tracheids, and parenchyma cells.

     - **Phloem:** 

Phloem transports organic compounds, primarily sugars, from photosynthetic tissues (source) to non-photosynthetic tissues (sink). It contains sieve tube elements, companion cells, and fibers.


**4. Secondary Vascular Tissue System (Secondary Growth):**

   - **Function:** 

In woody plants, secondary growth adds to the girth of the plant, providing additional structural support and increasing the capacity for water and nutrient transport.

   - **Components:** 

Secondary growth is facilitated by two lateral meristems:

     - **Vascular Cambium:**

This meristem adds secondary xylem (wood) to the inside and secondary phloem to the outside, contributing to girth.

     - **Cork Cambium (Phellogen):**

The cork cambium produces cork cells to replace the epidermis with a protective outer layer known as the periderm.


Together, these tissue systems and meristems constitute the internal organization of the plant body. The primary body consists of the dermal, ground, and vascular tissue systems, while the secondary body, primarily seen in woody plants, results from secondary growth driven by the vascular cambium and cork cambium. The different tissue systems and meristems work in unison to enable essential plant functions such as growth, photosynthesis, transport, and protection.