The Colors of Autumn Trivia Quiz

Answer: Carotenoids

During the growing season, most leaves appear green due to the presence of chlorophyll in their chloroplasts, where the process of photosynthesis produces carbohydrates from carbon dioxide and water. In late summer, chlorophyll replacement slows down, and the color of other chemicals in the leaves can be seen in place of the green. Carotenoids (yellow to orange in color) are also present in chloroplasts, where they absorb solar energy for photosynthesis and prevent photo-damage of chlorophyll. Humans can convert some carotenoids to retinal (a form of Vitamin A), and they are also useful as antioxidants.

Answer: Yellow phytochemicals are present all the time, red phytochemicals are only produced in autumn

While some plants have a significant amount of anthocyanins at all times (hence their red leaf color), in most deciduous trees they are only produced at the end of summer, when a decrease in the phosphate level in leaves changes the process by which sugars are broken down, leading to the production of anthocyanins. Worldwide about ten percent of trees produce anthocyanins; in the New England region of the United States over two thirds of the species do so, contributing to its famed autumn foliage.

The mixture of red and yellow pigments in leaves produces a range of colors, depending on their balance.

Answer: Evergreen trees

Evergreens keep their leaves all year round, and do not typically show seasonal changes in color (aside from some darkening of new foliage as it matures in some species, from light green to a darker green). In a forested area containing a mixture of hardwood trees producing various colors and evergreens, the contrast increases the perceived intensity of the colors. Since many of them produce an aromatic resin as part of their defense system, many associate the scent of pine and cedar with the colors, although they are independent.

Answer: Oak

Oak trees are members of the beech family. Their leaves are usually long and divided into segments, often with more rounded edges than those shown in the picture. Even more familiar is their fruit, a nut called an acorn, a number of which were also shown in the picture. Several of the leaves in the picture showed a mixture of red and green coloration; it is common for the veins in a leaf to stay green longer than the rest of it, leading to this kind of mixture, especially in the early stages of color development.

Answer: Yes

Every leaf loses chlorophyll independently of the rest of the tree, although they usually change at pretty much the same time due to being exposed to the same environmental conditions. As the yellow color emerges, and red is produced if the tree is one of those that does so, the mixed balance between the various phytochemicals in the leaves can produce a range of colors on a single tree.

It is common for color to appear first near the top of the tree, so the lowest leaves could still be green when the highest ones are fully colored.

Answer: You are seeing the cell walls

Once the chlorophyll is all gone, the tree's leaves have their strongest color. Then that, too, fades as the tree's metabolic processes continue to shut down. When all the phytochemicals have gone, you can actually see the cellulose in the cell walls of the leaf. Since they are not perfectly aligned, they reflect light in an overlapping pattern that produces a visual perception of brown color.

Answer: Cool clear days with frost-free nights

The yellow shades become visible in any climatic conditions, but the red-purple shades depend on the amount of anthocyanins being produced. The chemical reactions that produce them are triggered by cool weather (which is why they start to appear as the weather gets cooler in autumn) and proceed more rapidly when there is plenty of sunlight available. Cool clear days provide these conditions. Color development is also helped by chilly nights, with temperatures close to freezing, but not quite cold enough to produce frost.

The peak color period is only a few weeks, usually between early October (for northern and interior parts of Canada and the United States) and early November for more southerly areas. In the Southern Hemisphere, the color season is during the month of April, with the two-week climactic period varying from place to place.

Answer: In the mountains of Maui

Despite its tropical location, Hawaii is composed of volcanic islands, and has some high peaks where the temperatures are cool enough for deciduous trees to develop, and contribute their changing colors to the scenery of Hawaii. The tree in the image is located near the community of Keokea on the island of Maui, at an elevation of 872 m (2860 ft) above sea level.

In this region, the fertile volcanic soil and temperate climate make agriculture and forestry important industries.

Answer: Presence of many eager tourists

North America has a much greater variety of deciduous species than is the case in Europe and Asia, where the smaller number of species means there is a more limited range of colors. The dramatic changes between seasons ensure that many trees produce brilliant colors, and the fact that there are still large areas with (at least relatively) dense forest cover means the colored trees are readily seen.

The eager tourists are a result, not a cause, of the color. They are sometimes referred to as leaf peepers, a term which can carry negative connotations when used by those who are inconvenienced by their presence in rural areas which do not have the infrastructure to make tourist activities fit in without disrupting local residents. In Japan, where the image for this question was taken, tourism to see the autumn colors is called momijigari (maple tree hunting) or koyo (another way to pronounce the same characters, meaning leaves changing color).

Answer: Approach of the dry season

Especially in subtropical and arid regions, seasonal temperature changes are less important than are rainfall changes in determining when a deciduous tree drops its leaves, and hence may produce color in the process. Sometimes this rainfall change coincides with the winter, but not always.

The picture in the question shows the colors to be seen in the Adelaide Hills, near the capital of South Australia. This region was largely settled by German immigrants, who brought with them many familiar European deciduous species.