“Nature’s first green is gold/Her hardest hue to hold”
Robert Frost had a way of describing nature that forces the reader to both take notice of the world around them and to think about their own lives, their own experiences. The poem “Nothing Gold Can Stay” is both a meditation of the changing colors of leaves and of the brevity of beauty. From the first bright green of a new leaf through the point when “leaf subsides to leaf,” Frost imbues this natural progression with human emotions of loss. What do these changing colors really mean?
The different colors of leaves are due to three classes of pigments the leaves possess. Greens are due to chlorophyll pigment, which absorbs light for use in photosynthesis, the process by which plants turn light into usable sugars. Leaves appear green because these pigments absorb light in most of the color spectrum. Green is the only color not absorbed, and so that wavelength is transmitted to our eyes.
Yellow, orange and brown colors are due to a class of accessory pigments called carotenoids. Just like it sounds, these pigments also give color to carrots, as well as bananas, corn, and daffodils. In leaves, carotenoids work to absorb pigments that chlorophyll can’t, thereby allowing the plant to use more of the sun’s energy.
Finally, the red color of autumn leaves is caused by another accessory pigment, anthocyanin. In different plants, this pigment can appear red, purple, or blue. Unlike chlorophyll and carotenoids, anthocyanin does not participate in photosynthesis. Most anthocyanins are produced in the fall, in response to shortening days and less sunlight.
So the green leaves we see for most of the year actually contain several layered colors, hidden beneath the surface. Chlorophyll is continuously produced and broken down during the growing season, but as fall approaches, production slows and stops, and finally all the chlorophyll is destroyed. What we see in many deciduous trees are the remnants: yellows and oranges from the carotenoids that have been there all along, reds from anthocyanins appearing later in the season. Slowly, the leaves die.
It is difficult to not have a sense of loss as the seasons change around us. From year to year, after the bright pulse of autumn glory, leaves fall, green disappears, and it feels like an ending. It is hard to think of the world, reborn, in the spring. Though perhaps, as Robert Frost wrote, “nothing gold can stay,” we must remember that there will be new beauty in the world, new beginnings.
Think of this, always.
Frost, Robert and Edward Connery Lathem (ed.) The Poetry of Robert Frost: The Collected Poems. 1969 Reed Business Information, Inc. http://www.poets.org/viewmedia.php/prmMID/19977
Lee, David and Kevin Gould. 2002. Why leaves turn red. American Scientist 90(6): 524. http://www.americanscientist.org/issues/feature/why-leaves-turn-red
“Why Leaves Change” USDA Forest Service. http://www.na.fs.fed.us/fhp/pubs/leaves/leaves.shtm