Why do leaves change color?
Why do leaves change color in the fall and, well… fall?
The Wikipedia article on Autumn Leaf Color explains that “A green leaf is green because of the presence of a pigment known as chlorophyll … When abundant in the leaf’s cells, as during the growing season, the chlorophyll’s green color dominates and masks out the colors of any other pigments that may be present in the leaf. Thus, the leaves of summer are characteristically green.
Chlorophyll has a vital function: it captures solar rays and uses the resulting energy in the manufacture of the plant’s food – simple sugars which are produced from water and carbon dioxide. … During the growing season, … the supply remains high and the leaves stay green.
As autumn approaches, with daylight hours shortening and temperatures cooling, the veins that carry fluids into and out of the leaf are gradually closed off as a layer of special cork cells forms at the base of each leaf. As this cork layer develops, water and mineral intake into the leaf is reduced, slowly at first, and then more rapidly. During this time, the amount of chlorophyll in the leaf begins to decrease. Often, the veins are still green after the tissues between them have almost completely changed color.”
Leaves across the curriculum
Here are some selected library resources on autumn foliage from different subject-area viewpoints:
Above: Autumn Leaves by Thomas James Lloyd (watercolor painting, 1895, via Bridgeman Images: The Bridgeman Art Library in Credo Reference)
“What do red and yellow autumn leaves signal?” (article by Simcha Lev-yadun and Kevin S. Gould from The Botanical Review, 2007, via ProQuest Research Library)
“Melodic structure in Bill Evans’ 1959 ‘Autumn Leaves’” (article by Steven Strunk from Journal of Jazz Studies, 2016, an open-access journal included in OneSearch) – The jazz piano melody that Strunk analyzes is available for free via YouTube.
Autumn: season of flame (film by Kyoto Broadcasting System, 2009, 47 min., via Films on Demand) – Invites viewers on an autumn tour of scenery and temples in Kyoto, Japan.