In this lesson, you’ll learn about how a plant grows taller and how this is different from a plant growing wider. You’ll also learn about the types of tissues produced during primary growth and the functions of those tissues.
Types of Plant Growth
As you grow and develop from childhood you get taller and bigger overall. But at some point you reach a maximum height. This type of limited growth is called determinate growth, which means is that once you have reached your maximum height (which is determined by your genetics), you can’t grow any taller. This is something that you have no control over.Plants, unlike animals, have indeterminate growth, which means that they can continue to grow taller as long as they are alive. Most plants tend to slow their growth at some point, but as long as they wish to keep growing they may do so.
All plants experience what is called primary growth. Primary growth is the upward growth of the stem and the downward growth of the roots. It is the type of growth that makes a plant longer.Some plants experience an additional type of growth called secondary growth, which occurs in plants known as dicots, such as trees, shrubs, and vines. Secondary growth is the outward or lateral growth of a plant, which makes it thicker and wider. Dicots need secondary growth because they tend to grow taller than other plants and need the extra support. Without secondary growth, a tall pine tree would be just like a very long blade of grass.
How Plants Grow
Much like how your body grows, plants grow through a process called cell division. Cell division produces new cells that enable a plant to grow longer. These cells make up tissues called meristems, which all plants have. A meristem consists of unspecialized cells that divide and generate new cells.
Meristems that are found at the tips of roots and buds are called apical meristems, and these are the meristems that are responsible for primary growth in plants. Any tissues that are produced during primary growth are called primary tissues.
There are three types of tissue that arise during primary growth: dermal, vascular and ground. The dermal tissue system is the plant’s outer protective coating. Much like your skin, the dermal tissue protects the plant’s internal organs from physical damage and disease.The vascular tissue system is made up of xylem and phloem and provides support and long-distance transport of water and nutrients between the roots and other parts of the plant. Xylem and phloem produced during primary growth is called primary xylem and primary phloem, while vascular tissue produced during secondary growth is called secondary xylem and secondary phloem.
The ground tissue system is any part of the plant that is not dermal or vascular tissue. It fills the spaces between the dermal and vascular tissues, and has a variety of functions, including photosynthesis, nutrient storage, and structural support.
Let’s review! All plants experience primary growth, which is the lengthening of both roots and stems. This growth occurs because of cell division in apical meristems, which may continue indefinitely in plants. Plants that experience secondary growth can grow taller than those that only experience primary growth because they have extra support from their lateral growth.
Primary growth produces primary tissues in all plants, and these tissues systems provide food, storage, and structure.The three types of tissue that arise during primary growth include dermal tissue, which is the plant’s outer protective coating, vascular tissue, which is made up of xylem and phloem and provides support and transport of nutrients between the roots and other parts of the plant and ground tissue, which is any part of the plant that is not dermal or vascular tissue.