1. The roots help provide support by anchoring the plant in one place. They also absorb water and nutrients from the soil or other medium, and store sugars and carbohydrates needed by the plants for other activities. Plants can have either a taproot system, like a carrot, or a fibrous root system, like many kinds of grass, or an adventitious root system.
(For illustrations: Roots )

2. Stems carry the water and nutrients up from the roots and distribute them to the leaves, using xylem cells. From there, they carry the food produced by the leaves back to other parts of the plant, using phloem cells. Stems also help the plant to position itself for some serious sunbathing.       
      (Click picture to enlarge.)

3. The plant's leaves are the food-makers, where photosynthesis occurs. There are many different shapes and sizes of leaves, but they can be grouped into two categories:  simple, with just a single leaf blade connected to the stem, or compound, with the leaf blade divided into many parts before it attaches to the stem.
                                                                                            (Click picture to enlarge.) 

4. Flowers are not just pretty and perfumed; they contribute in many ways to the survival of plants. The flower has both male and female parts, which combine to pollinate the plant, forming seeds and fruits. The flower also attracts pollinators, such as birds, bees and bats. The pollinators help the growth and development of the seeds and fruits. 
                    (For illustrations: Flowers )