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What do you have in common with a plant? Well, besides needing sunlight and lots of water, you have organs that are made up of tissues. That’s right, tissues make up you, non-human animals, and plants. Plant tissues and tissues of other organisms help carry out specific functions, like transporting water, minerals, and oxygen throughout their bodies!
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Jetzt kostenlos anmeldenWhat do you have in common with a plant? Well, besides needing sunlight and lots of water, you have organs that are made up of tissues. That’s right, tissues make up you, non-human animals, and plants. Plant tissues and tissues of other organisms help carry out specific functions, like transporting water, minerals, and oxygen throughout their bodies!
A plant tissue is a group of cells working together in one or more functions and form part of the plant organs.
Tissues in general are a group of cells that work together to perform a function. So, when tissues work together, organs are formed. Plant tissues make up the organs of plants, including the leaves, the stem, and the roots.
There are typically two types of plant tissue groups to start with: meristematic tissue and permanent tissue.
Meristematic tissue is plant growth tissue that contains cells that are undifferentiated meaning they have no specialized shape, function, or size yet. Meristematic tissue cells differentiate to become a certain type of tissue with certain qualities.
When it differentiates, it becomes permanent tissue, which makes up the three main classifications of plant tissue we are concerned with.
Compare the tissues in this micrograph to the ones in the diagram in Fig. 6 at the end of the article.
Meristematic tissue in plants is undifferentiated tissue with no specialized function yet (like stem cells in animals). When it differentiates it becomes permanent tissue.
Permanent plant tissue is divided into three groups: dermal, vascular, and ground.
Dermal tissue is the outermost layer or layers of tissue that surrounds the plants,
the vascular tissue is the tissue associated with the vascular system,
and ground tissue is the tissue that is not epidermal or vascular and makes up a large percentage of the plant tissue.
All vascular plants undergo the primary growth of stems and roots. Primary growth is characterized by cell division and cell growth that will increase the length of the plant. Typically, plants that are considered herbaceous will only undergo primary growth.
Woody plants may undergo another round of growth known as secondary growth. Secondary growth is lateral growth that increases the width of a root or stem. This occurs through the production of new vascular tissue (secondary xylem and phloem) which is produced from the lateral meristem (cork cambium and vascular cambium). The older xylem does not function for transport but continues to support the plant, allowing plants exhibiting secondary growth to grow larger.
The dermal tissue in plants has a similar function to your own skin, protecting the plant organs and helping to prevent water loss!
Did you know that "dermis" means skin?
Dermal tissue in plants is made up of epidermal cells that are usually small, round, and may or may not have a vacuole. These epidermal cells make up the outer cell layer(s) of plant organs and their main function is to protect the plant organs from the climate or pathogens. Epidermal cells also secrete a cuticle, which is a waxy layer that provides extra protection against water loss and UV rays from the sun.
Epidermal cells may become specialized in their later development, depending on the organ they protect, and may become trichomes, stomatal guard cells, or root hairs.
Trichomes are protective projections on stems and leaves,
the stomatal guard cells control gas exchange in leaves,
and root hairs help increase root surface area.
Ground tissue in plants includes all of the tissue that is not vascular or dermal. This means a lot of the plant tissue is actually ground tissue. Ground tissue in itself is diverse and has various functions, including:
Storage
And structural support.
The three types of cells associated with the ground tissue, which we describe in the next section, are the collenchyma, the parenchyma, and the sclerenchyma.
There are many examples that we can delve into showcasing tissue in plants, here we focus on examples of ground tissue in plants: collenchyma, parenchyma and sclerenchyma.
The collenchyma cells are typically long and fibrous and they provide support for the non-woody parts of the plant including the stems of herbaceous plants and petioles (the part that attaches the leaf to the branch). Unlike the other ground tissue cell types, the collenchyma cells do not have a secondary cell wall, making them more flexible.
Collenchyma tissue may be more noticeable than you think. Have you ever eaten celery (the stem) and realized if you rip a piece in half, stringy, strong hair-like fibers remain? Well, those fibers would be collenchyma tissue.
The parenchyma is the plant tissue mostly involved in photosynthesis. In fact, the mesophyll tissue in leaves is made up of parenchyma cells, where photosynthesis occurs, thus some parenchyma cells contain chloroplasts (Fig. 3). The parenchyma cells can also act as storage sites, especially in the cortex and pith of certain roots.
For example, the cortex of carrots is parenchyma tissue for storage.
Parenchyma cells help in the wound healing process for plants because, unlike other cells after differentiation, this is a plant tissue that retain the ability to divide.
The sclerenchyma cells are mainly for support. They have a thick secondary cell wall and are fortified with lignin. Lignin is a rigid polymer that helps provide support in woody plants and in some nuts and seeds. Oftentimes, these cells will undergo programmed cell death (apoptosis) and exist merely as structural support. The two types of sclerenchyma cells are fibers (support for woody stems) and sclereids (protection in nuts and seeds).
Biting into a stone fruit like a peach, cherry, or a plum, you might be aware of those pesky central pits. Those pits are tooth-breakers because they are made up of hardy sclereids (sclerenchyma tissue).
The vascular tissue in plants consists of the xylem and the phloem, which transport water and food/nutrients respectively.
Vascular tissue exists in the roots, stems, and leaves, connecting them to ensure that each plant organ can get the necessary nutrients and water it needs for survival. Water and minerals only flow through xylem tissue in one direction, and food and nutrients flow in both directions through the phloem.
The xylem tissue of most plants is made up of:
Tracheids: Tracheids are long cells that are fortified with a strong polymer called lignin and are typically dead at maturity (they undergo apoptosis). Tracheids are thought to be the earliest conductive cell in the vascular system.
Vessel elements: Vessel elements are shorter and wider than tracheids, and are not fortified with lignin. They are specific to flowering plants (angiosperms).
The apoptosis that the xylem tissue cells undergo allows the cells to have holes in their cell walls so that water and minerals can pass through easily.
The phloem tissue of most plants is made up of:
Sieve elements: In flowering plants, the sieve tube elements are long cells connecting at the end that have cytoplasm but few organelles. The ends have plasmodesmata which become bigger to allow for nutrient transport, these ends are known as sieve plates. Unlike in cells of the xylem tissue, these cells do not undergo apoptosis when they mature.
The arrangement of tissues in plant organs may vary depending on the group of plants. The monocots and dicots, the two main groups of flowering plants, have different arrangements of vascular tissue throughout their roots, stems (fig. 5), and leaves.
A plant tissue diagram illustrating the various permanent tissue types found in vascular plants. Once the plant differentiates, three main tissue types present themselves: dermal, ground and vascular. Each organ of a plant - roots, stems or leaves - contains these tissues for specific reasons as laid out in the sections above.
The main types of tissues in a plant are:
The function of each plant tissue is:
Vascular tissue in plants is the tissue associated with the plant's vascular system. The vascular system transports water and minerals from the roots to other plant parts and food from where it is produced to where it is needed or stored.
The two types of vascular tissue in plants are the xylem, which transports water and minerals, and the phloem, which transports food (sugars).
A tissue is a group of cells that works together to perform a specific function. In plants, these groups of cells are called plant tissues. For example, the epidermal cells of plants work together to cover and protect the plant and form the dermal tissue. Plant tissues work together to form plant organs, which are the stems, roots, and leaves.
The ground tissue is found all throughout the plant, in the leaves, roots, stems, and even reproductive structures.
In the leaves, the ground tissue is called the mesophyll tissue and is where photosynthesis takes place. In the roots, ground tissue is largely used for storage. In the stem, it helps to provide structural support and acts as storage as well.
What are the three types of permanent plant tissue?
Ground, vascular, and dermal
T or F: Plants don’t have organs; they only have cells and tissues.
False
What is the purpose of the vascular tissue in plants?
Transport water, food, and minerals from one part of the plant to another.
What is the purpose of the dermal tissue in plants?
Become specialized cells that help deter herbivory or absorb more water.
What is the purpose of the ground tissue in plants?
Serve as storage of food produced by the plant.
T or F: Dermal tissue (epidermal) cells can specialize to become trichomes, stomatal guard cells, or root hairs.
True
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