I captured this image of a single dandelion the other day.

Dandelion clock

It's just a simple dandelion; yet I used three flash units to create the photograph:

• My main light is a Nikon SB-900 positioned camera right and placed inside of a Lastolite EXYBOX softbox. The speedlight was set for TTL -1EV exposure.
• My rim light is a tiny Nikon SB-R200 speedlight positioned behind the dandelion camera left and facing the subject. This speedlight was set for TTL +1EV exposure. 
• My background light is another Nikon SB-200 speedlight positioned camera left. This speedlight was set for TTL -1.7EV. I placed a blue gel over this light and faced it towards a small piece of white foam board in the background.
• All three lights were then triggered remotely using the SU-800 wireless transmitter.

I used the Nikon D800 camera and Nikon 200 f/4 Micro lens for this picture. The exposure is 5 seconds, f/20 at ISO 100. Given that the room was quite dark, any shutter speed faster than 10 seconds removes any trace of ambient light--leaving the flash units to provide the entire exposure. Of course, the camera/lens is secured to a stable tripod.

Changing the gel color of the background light quickly provides a different background color with very little effort:

Dandelion clock But, I prefer the blue one as I think it looks more like the dandelion is being photographed in front of a clear, blue sky.