As Gary said, it's from pigments.
Pigments called anthocyanins
which are pigments found in plants that make them turn red in the fall
and are found in other plants as flavenoids which gives them a multitude of colors.
And speaking of cyanins, which really has nothing to do with anything, but it's the same root as cyanosis--
My oldest son won his school's spelling bee when he was in the 5th grade. At the Regional Spelling Bee, he came in 8th place, out of about 200 kids, from 4th graders through high school seniors.
The word he got out on was "acrocyanosis."
When they gave him that word, my father leaned over and said to me, "Now they're just making stuff up."
But now, for the rest of our lives, should anyone have have need for it, my son and I will be able to spell acrocyanosis for them.
Acrocyanosis is blueness or pallor of the extremities usually associated with pain and numbness and caused by vasomotor disturbances.