Two words meaning "autumn-colored foliage" are koyo and momiji, both written with the same two characters, 紅葉. Koyo refers to the phenomenon of changing autumn colors, mainly when it occurs to the leaves of deciduous broad-leaf trees before the leaves fall to the ground.
At some point in time, the word momiji became synonymous with the maple tree (kaede), the most beautiful of the autumn trees.
The species of maple generally determines the color the leaves will change: red, yellow or brown. Although the word koyo literally means "red leaves, " it is used to refer to all the colors of autumn leaves. The word oyo refers to yellow leaves, and the word katsuyo refers to brown leaves specifically.
The koyo season in Japan typically begins in mid-September in Hokkaido to the north, gradually spreading to the southern end of the Japanese archipelago in about 50 days. The change occurs when the low temperature at dawn is about 6 degrees or 7 degrees Celsius, and the viewing season lasts for 20 to 25 days. The exact timing to see the leaves fluctuates somewhat from year to year.
Maples (fullmoon, Japanese, trident), Japanese sumac, wax tree, Japanese rowan, burning bush, rhododendron
Maples (painted, linden-leaved), ginkgo, poplar, plane tree, Japanese elm
Japanese beech, oaks (Quercus crispula, daimyo, sawtooth, konara), chestnut, birches, Japanese zelkova, Japanese horse chestnut, bigleaf magnolia
When autumn deepens and the leaves begin to turn color in the fields and mountains, "hunting for autumn foliage" is a popular pastime in Japan.
Taking outings to appreciate the beauty of autumn has been a custom since the ancient collection of Manyoshu poetry was compiled in the eighth century, and there are scenes that involve "hunting" for beautiful autumn colors in the classical Heian Period novel "The Tale of the Genji." The practice of writing the words koyo and momiji with the same characters goes back to Heian times, and a large section of the Kokin Wakashu poetry collection, compiled around the beginning of the same period, is dedicated almost entirely to autumn leaves. For as long as there have been seasons in Japan, the colors of trees have been a symbol of autumn, just as the cherry blossom is a symbol of spring.
Today, going on a picnic or a drive to the mountains or countryside to gaze at the beauty of autumn is a common pursuit.