There are four main parts of a plant, each of these parts have specialised functions that allow the plant to function

Roots

The main functions of the roots are:

• Anchor the plant to the ground
• Absorb water and dissolved nutrients
• Store food
• Absorb oxygen

Root hairs increase the area for water absorption and are replaced by the plant every few days

Stems

The main functions of the stems are:

• Support the leaves, flowers and fruit
• Transport water and nutrients (mineral salts) from the roots to the growing parts of the plant through the plants xylem
• Transport manufactured food to from the leaves to the growing parts of the plant through the plants phloem

Leaves

The main functions of the leaves are:

• Manufacture food through photosynthesis
• Transpiration, which is the loss of water through evaporation
• Respiration

The leaves are constantly filtering a stream of air through their tissues to extract carbon dioxide which is combined with water to make carbohydrates in a process called photosynthesis.  The carbohydrate provides food for the entire plant.

Plants can loose up to 98 percent of their water intake through transpiration, this is a necessary loss to ensure that nutrients and carbohydrates flow freely through the plant

Flowers

The only function of a flower is reproduction.

Flowers are made up of several part

• Petals (corolla) which are used to attach insects
• Sepals (calyx) to protect the flower bud
• Stamen (anther, filament) produces pollen which contains the male gamete
• Pistil (stigma, style) which holds ovules which contain female egg cells

Important Plant Processes

Photosynthesis

Photosynthesis is the process by which plants manufacture food.  The plant uses energy from light to build up plant food from water and carbon dioxide.  This process takes place only where there is green colouring in the leaves, the green pigment is called chlorophyll.  For photosynthesis to take place there needs to be a good supply of carbon dioxide (CO2) present; plenty of water from soil, hydroponics, air; light of certain wavelengths (red, blue/violet)

If there is not enough nutrients in the leaves, photosynthesis will stop and often will result in yellowing of the leaves.

Respiration

Sugars produced by photosynthesis are converted into energy by respiration.  All living parts of a plant respire at all times.  When a plant makes more food by photosynthesis than it uses in respiration or other growth processes the food accumulates for future use, this is of great importance for the production of fruit.

Transpiration

Transpiration is the process by which water passes out through the stomata on leaves as water vapour.  Water is continuously moving from the roots up through the plant.  Increasing transpiration increases the amount of nutrients being taken in by the roots of the plant.