The Parts of Plants
Plants have many parts, each of which tends to have multiple functions. The various parts of plants (or organs, as they are often called) are made from different types of tissue. Tissue is made from cells, which are the building blocks of plants. The cells divide and specialize to form multiple types of tissue which combine to create roots, stems, buds, leaves, flowers, fruits, and seeds. Each of these plant parts will be covered in more detailed on subsequent pages.
There are two main types of plant tissues that make up the various parts of plants:
- Meristematic tissues (or meristems)
- Permanent tissues
Meristematic tissue is made of cells that are identical which actively divide to generate new cells. These meristematic cells then undergo a process called differentiation, whereby these identical cells develop and grow into cells that are different from one another and different from meristematic cells. These differentiated cells combine to make tissues and organs.
Apical meristems are found at the tips of shoots and roots. As the apical meristems multiply by dividing, they elongate which lengthens the stem and roots. This is the primary way that plants grow.
While apical meristems allow plant stems to grow taller and their roots to grow deeper into the soil, lateral meristems cause secondary growth in stems and roots, making them thicker and increasing their girth. This helps to make the plant stems and roots stronger adding stability and support.
There is a third type of meristem called intercalary meristem that exists in grasses. It is located at the base of each leaf and produces new cells that regenerate leafy growth when the grass is mowed or grazed.
Once meristematic tissue is fully differentiated, it becomes permanent tissue. Permanent tissue is classified as either simple tissue, consisting of only one type of cell, or complex tissue consisting of multiple cell types. The epidermis is an example of simple tissue. Xylem and phloem are examples of complex tissues.