Heavy overnight rain and winds have taken their toll on the autumnal colours, russets, browns and yellows. On the lower path in Newton Wood, a yellow carpet of fallen hazel leaves covers the woodland floor. With the onset of shorter days and cooler temperatures, complex chemical changes occur in the leaves. The concentration of sugar increases and chemicals called anthocyanins and carotenoids produced. These absorb green and blue light while reflecting red and yellow giving them the familiar orange colours of autumn. Yellow leaves, on the other hand, are the result of a different process. A particular carotenoid called lutein is present in leaves all the year but dominated in the summer by chlorophyll which gives the leaves their green colouring. Come the autumn chlorophyll degrades more rapidly than lutein, the green hues giving way to yellow.
The Bard wrote about the yellow leaves of autumn in his Sonnet 73:
That time of year thou mayst in me behold
When yellow leaves, or none, or few, do hang
Upon those boughs which shake against the cold,
Bare ruined choirs, where late the sweet birds sang …