Images with a black & white background and a coloured feature are a little old hat now but make a good exercise in using "Select Color" in the image editor.
I recommend you pick an image with a limited range of colours. The sample below basically had magenta (flower), yellow (leaves) and red, (the soil background).
The attachments show the original, version 1 with only the magenta flower coloured an version 2 with the flower & leaves coloured.
Let me see some of you rise to this challenge before Fred does.  
Terry

Some more clues on how to do this: see screen shots of the Sel Col tab below.
The first is for the image where only the magenta flower shows coloured. I first made the whole image B&W using the Sel Col pre-set; then I modified the magenta row.
The second is where I modified the red row only - the Sel Col dropper indicated that the soil background was a red tone so that was neutralised leaving the yellow/green leaves and magenta flower.
Terry