stem
Definition
A stem is the part of a plant that grows above the ground. It is the main axis of the plant, and it is responsible for supporting the leaves, flowers, and fruits. The stem also transports water and nutrients from the roots to the rest of the plant, and it stores food and water.
The structure of a stem varies depending on the type of plant. Some stems are simple, with a single central axis. Others are branched, with multiple axes. The shape of the stem can also vary, from round to cylindrical to flattened.
The internal structure of a stem is also complex. It is made up of different tissues, each with a specific function. The epidermis is the outermost layer of the stem. It protects the stem from the environment. The cortex is the layer of tissue beneath the epidermis. It stores food and water. The phloem is the tissue that transports sugar from the leaves to the rest of the plant. The xylem is the tissue that transports water and nutrients from the roots to the rest of the plant.
The stem is an important part of the plant, and it plays a vital role in the plant's survival.
How can the word be used?
The water flowed from the broken pipe, but I was able to stem the flow with a rag.
Different forms of the word
Noun: stem (plural: stems).
Verb: to stem.
Adjective: stemmed.
Etymology
The word "stem" comes from the Old English word "stemn", which means "trunk of a tree". It was first used in English in the 7th century.
The word "to stem" means "to stop or prevent the flow of something".
The word "stemmed" is the past participle of the verb "to stem".
Question
What is the role of the stem in a plant?
AQA Science Exam Question and Answer
Question:
Explain the structure and function of plant stems. Discuss the role of vascular tissues within the stem and how they facilitate the transport of water, nutrients, and sugars throughout the plant.
Answer:
Plant stems are essential structures that support the plant, hold leaves for optimal sunlight exposure, and serve as conduits for transporting vital substances. The stem consists of different layers, including the epidermis, cortex, and vascular bundles. Vascular tissues, comprising the xylem and phloem, are critical components of the stem's function.
Xylem, responsible for water and mineral transport, contains vessel elements and tracheids. These cells form continuous pathways, enabling water to move from the roots to the rest of the plant. Phloem, on the other hand, is responsible for transporting sugars produced during photosynthesis, distributing energy to growing tissues and storage organs.
Vascular tissues create a network of channels, known as vascular bundles, running longitudinally within the stem. As water and nutrients are absorbed by the roots, xylem vessels transport them upward. Concurrently, sugars synthesised in leaves are transported downward through the phloem, ensuring a balanced distribution of resources.