I saw Compound Chem had made a wonderful infographic about the chemicals that produce the brilliant coloured leaves this time of the year and so I sent the link to my Dad, an avid gardener. He then replied to me with a poem, another of his hobbies, that he'd written a few years ago describing the changes to the leaves with a chemical insight.
The colours in the leaves
Once the green of chlorophyll,
Didst verdant scenes on yonder hill,
Fill with glowing hues its summer’s glory,
And leaves shine forth to tell a chemist’s story.
As leaves do turn to feed from moistened light,
And deadly gas from which these leafy leaves will soon take flight.
How silently, as autumn ushers in bright days yet frosty nights,
These many-hued greens give way to other sights.
Other forms usurp the molecular green-maker’s robe,
And from their secret lair these tribes with ear-harsh names do probe.
So chlorophyll succumbs to xanthophyll,
No more such verdant scenes on yonder hill,
And carotene and anthocyanins do hold the day,
And orange, yellow, red and gold do sway.
Yet does not summer green pass to autumn splendour,
And to us cold breezes crispness render.
Peter Branson 2007