The plant shoot system is a complex network of a number of different parts all working to keep the plant healthy and growing.
It is fascinating how much is involved in what we usually look at as a simple living organism. We will investigate the shoot system here.
The Structure of the Shoot System
A plant has many complicated and complex systems that keep it living and growing, including the shoot system. When referring to the shoot system in a plant, we generally refer to the leaves, buds, flowering stems and flowering buds, as well as the main stem itself.
The word ‘shoot’ generally is used when talking about the main stem.As we move from the ground surface to the terminal bud (end of the undeveloped shoot) we will encounter nodes and internodes. Nodes are the points where leaves are attached, and internodes are the places on the stem between the nodes. In the crux created by the node and stem, there are axillary buds that lay dormant but have the potential to grow a vegetative branch.
These axillary buds lay dormant because of apical dominance.
This is a phenomena where the plant concentrates most of its resources at the terminal bud. The terminal buds grows at the apex, or tip of the plant. This is responsible for making the plant grow taller and bigger so it makes sense that the plant would want to concentrate resources here. If the terminal bud gets damaged, the axillary buds will ‘wake up’ and begin to grow, saving the plant.If the axillary buds begin to grow, they can create their own terminal buds, leaves, etc. They, in a sense, create a secondary plant themselves.
If you own any houseplants, you might understand the idea of pruning them to create ‘bushy’ plants. Well, this is because you are removing the terminal bud that stimulates the axillary buds to grow, creating that thicker looking plant.As is commonly known, the leaves of the plant act as the photosynthetic factory for it, producing sugars and other compounds for the plant to survive on. There are many different types of leaves, but most will include a blade, stalk, veins and the petiole.
The stalk is the main stem of the leaf, the blade is the actual green leaf portion, and the petiole is where it attaches to the node. The veins are similar to our veins in that they carry water and nutrients out into the leaf.
The Interior Structure
Inside of the shoot are primary and secondary tissue structures. There is dermal tissue that acts similar to our skin, the ground tissue that acts to give support to the plant, and finally the vascular tissue.
The dermal tissue acts as a waxy coating to protect other tissue from drying out. The ground tissue is around the vascular tissue and helps give the plant the support it needs. It is similar to a skeleton. Finally, there is the vascular tissue that attaches to the veins in the leaves. This is responsible for getting nutrients around the plant.In certain plants, there is a secondary tissue structure called the vascular cambium and the cork cambium. In the vascular cambium, new tissue is constantly being made that replaces vascular tissue in the plant.
As the plant ages, new tissue forms and old ones harden, forming rings (like when you cut a tree down). The cork cambium helps to create the bark of the plant, further protecting it from outside harm.
The Function of the Shoot System
The shoot system works closely in part to the root system of the plant. The shoots are able to absorb nutrients via the plant’s different roots.
The water and other nutrients that are taken in are shuttled up through the plant’s vascular system located in the shoot. It moves up through the shoot to the leaves of the plant, distributing out across the leaf veins to the different sites where the nutrients are needed.Once the nutrients have arrived where they need to be, the plant can use what it needs in the process of creating food and energy for itself during photosynthesis. This occurs in the leaf’s chloroplasts, which is the reason that the plant’s leaves are so very important. The leaf is also responsible for collecting more water as well as oxygen, carbon dioxide and sunlight. Without these components, the plant would not have a chance at survival.
Let’s review. The shoot system consists of the stems and leaves of the plant. More specifically, it includes the nodes, internodes, axillary buds, terminal bud and leaves. The leaf has four parts as well, the stalk, blade, veins and petiole. Each part works to keep the plant alive and functioning properly.
The shoot system uses the root system to draw up water and nutrients and deliver them to where they need to go in the plant’s leaves. Once there, the leaf will use these materials in photosynthesis as the leaf absorbs sunlight.
Following this lesson, you’ll be able to:
- Describe the structure of a plant’s shoot system
- Explain how a plant’s shoot system and root system function together