Plant parts
Plants are made up of many parts. Each part has a different function and they all work together to help the plant grow and reproduce.
The external plant structures are on the outside of the plant and are the ones you can see, for example, the leaves.
Internal plant structures are inside the plant and are the ones that we cannot see easily unless we have a magnifying glass or microscope. An example is the xylem (water-conducting tissue).
External plant structures
Click on the label for each plant part in the diagram below to find out more.
Roots
The roots are made up of:
- xylem tissue, which transports water and dissolved minerals
- phloem tissue, which transports sugars made in the leaves to other areas
- root hairs
- root cap and growing tip.
A large spreading fibrous root.
Beetroot has a taproot, which stores food and starch.The function of roots is to:
- hold the plant in the growing media or soil
- act as the main transport system of the plant and take up water and dissolved nutrients
- store food in the form of starch.
Adventitious roots
Adventitious roots are roots that form from unusual places on the plant such as from stems or leaves. Plant propagators use the ability of plant parts to produce adventitious roots to make more plants. Some weeds are also very good at developing adventitious roots in unusual places on a plant. This helps them to survive and multiply when other plants would die.
Stems
The function of the stem is to:
- provide the transport system between roots and shoots
- carry water and minerals in the xylem from the roots to the leaves
- carry food and sugar in the phloem from the leaves to the roots
- support and hold up the plant to the light and air
- carry out a small amount of photosynthesis.
The cells that make up xylem and phloem together form the vascular bundles (veins) in the stem.
Vascular bundles can be seen when a celery stem is cut.
This diagram shows the vascular bundles in a stem. Both xylem and phloem are present in each vascular bundle.As plants mature, the vascular bundles get bigger, and gradually join up to form a whole ring around the stem. That's why you see rings in tree trunks.
In a mature plant, bark forms to protect the trunk. The cambium cells are cells that divide to form new cells for plant growth.Leaves
Leaves come in all sorts of shapes and sizes.
This is the leaf of a Gunnera manicata. It has very large leaves.
Leaves of the tree fern are placed to get maximum sunlight.
Leaves are made up of a blade (or lamina) and a short stem called a petiole. A node is the point on the stem where the leaf is attached. The veins in the leaf transport food and water. (Dicotyledon plants include most flowering plants. They have seed embryos with two cotyledons.)
Leaves have three main functions:
- making food through the process of photosynthesis
- releasing water vapour from the underside of the leaf during transpiration
- gas exchange – the giving and receiving of oxygen and carbon dioxide from the air.
Buds
Buds are undeveloped shoots. All buds are important because this is where cells are dividing and growing. These can produce leaves and stems or flowers, followed by fruit.
The lateral bud is found at the node on a stem. The apical bud (sometimes called the terminal bud) is the top bud at the growing point of the plant.
Internodes are the sections of stem between the nodes.
This is a lateral leaf bud of an apple tree.
Flowers
The main function of a flower is reproduction. The structure and colour of a flower will depend on how it is pollinated.
Insect-pollinated flowers are usually colourful and/or scented. 
Wind-pollinated flowers are often individually small scentless and not very showy. They also produce a lot of pollen.
Timothy grass is another example of a wind pollinated flower.Seeds
The seed is made up of an embryo (new plant), a food store and a protective seed coat.
The main function of seeds is to spread and create a new generation of plants.
Fruit
The ripened ovary of the flower develops into a fruit.
The fruit of the apple protects its seeds and helps with seed dispersal.
Key points
- Plant parts all have special functions to help the plant grow and reproduce.
- The external plant structures are on the outside of the plant and are the ones you can see, for example, the leaves.
- Internal plant structures are inside the plant and are the ones that you cannot see easily unless you have a magnifying glass or microscope. An example is the xylem (water-conducting tissue).
What's next?
Go to: 2 Plant processes.