Microscopy Image Gallery

Exploration of the Month

August 1998

middle of sunflower

the florets

The flowers at the center of the plant are called florets. They are arranged in a circular pattern. The cross-sectioned picture below shows the placement of the florets. Nectar which bees use to produce honey is contained deep within the florets.

The florets' main function is to help with the reproduction of the sunflowers. Contained within them is an organ called the stamen which has pollen on it. When insects like bees and butterflies visit the sunflower, they collect pollen on their legs and bodies. As they move around on the plant, the pollen is transferred to the stigma. On the picture of the individual florets below, the stigma are the two tiny branches which have the black tips.


middle cross section individual florets SEM image 40X


floret 2.5X outside lining 2.5X SEM image 40X

SEM image 1000X


Here are some magnified images of a single floret. On the above left is a photo which shows the hairlike projections from the floret. The picture in the middle is its outside lining. The white bar represents a distance of 100 micrometers or 1/10 of a millimeter. The other two pictures were taken with the scanning electron microscope. The one to the right displays the opposite tip of the floret which is connected to the flower. Do you see the tiny fiber projections? Why do you think they are there? To the left is a close-up view of these fibers, magnified 1000 times.


Below are magnified images of the stigma. The stigma is the part of the flower which collects the pollen for reproduction. These pieces seem to be composed of tiny fibers too. The fibers brush against the insects' legs and collect the pollen.

outside lining 2.5X SEM image 200X SEM image 1000X


When the pollen comes into contact with the stigma, the reproduction of the sunflower begins. At the end of the floret, a seed develops. Towards the end of the summer when the sunflower wilts and falls over, all of the florets have seeds attached to them. These seeds begin the life cycle all over again next year.

sunflower seeds Sunflower seeds have many uses and are harvested by the farmers who grow sunflowers. Below is a closer view of the outer shell of the sunflower seed assisted by the optical microscope. The seeds can be compressed into an oil which is used for cooking. The oil is also added to soap and paints as a lubricant. Perhaps their most enjoyable use is food. The seeds are dried, salted, and shipped to people who enjoy them as a snack.

sunflower seeds 10X

Main Sunflower Page





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Last Updated: 8/03/98