X is for Xanthophyll

I can't tell you how pleased I was to find Xanthophyll to put in my autumn alphabet.  It's probably the most autumnal word in my list but I'd never heard of it.  And I would take any X word!

Xanthophyll is a natural yellow pigment found in plants.  In the summer it is masked  by chlorophyll which is the green pigment essential for photosynthesis.  It helps protect leaves from damage caused by too much sunlight.  As autumn arrives, chlorophyll breaks down. The yellow xanthophyll pigments remain visible, giving leaves their yellow and golden colours.  It's there all the summer and it's only towards the end of the life of the leaf that it is revealed.  

So now you know too!  (If you didn't already.)