Dazzling Fall Colours That Mystify

The trees keep many hidden secrets. Underneath the green foliage lies a mesh of fiery colours which are waiting to uncover in the coming season. The leaves in the summer and spring are rich in chlorophyll. Chlorophyll is responsible for the green pigment in the foliage. Essential for survival of the tree, chlorophyll plays a significant role in producing energy for the plant with help of sunlight. Chlorophyll is responsible for the associated chemical reactions with carbon dioxide in air for food production. Along with necessary sugars and moisture, it also produces oxygen, which is released in the atmosphere, so important to humans for their survival.

Camouflaged in the leaves are other pigments that are revealed only in Fall. These golden, yellow and orange palettes of pigments are known as carotenoids. The carotenoids begin their journey when the leaf is born, they are there along with chlorophyll in the leaves. However, they do not work till chlorophyll is doing the job. These hidden sentries come into picture only when the days are becoming smaller and there is less sunlight.  They do not easily break down like chlorophyll. However, they are essential for the survival of tree when the sunlight is dim. The intense yellow and orange carotenoids intensify consuming whatever sunlight is there to be absorbed. The red fiery colour of foliage ensures the same.

The ideal conditions for a brilliant display of Fall foliage are indeed a rain-free, frost-free weather. Bright days although with less comparative sunlight and dry spell triggers the autumn season’s peak colours.  A number of other conditions trigger the foliage to change hues including soil pH, temperature and sun.

Anthocyanins, the pigment that are produced only during Fall at low temperatures and cool nights expedite the demolition of the green substance chlorophyll. Excessive pH values of soil make anthocyanins blue. This happens when the soil is alkaline. When the soil is acidic, anthocyanins become red. In between the spectrum of pH for soil, they take the colour violet. Anthocyanins exist in three dominant colours, blue, red and purple.

Excessive rains wash off the leaves. Frost is another reason for frozen leaves quickly parting from the tree.

While nature has a way to impart the colours from deep yellow and oranges to red and crimson. Humans have no way to impart a name to all the colour palettes the leaf goes through during its life cycle. I saw few names that are fun and perhaps easy to remember:

Chilli pepper red

Peach pink

Sugar Almond

Amberglow

Samba

Sandstone

• OUTDOOR DISCOVERY, Nature’s Color Palette by Abby Alger
• The Science of Autumn Beauty, International Society of Arboriculture