The Rainbow Flora

There are many leaves in the plant kingdom that defy the natural green to splash colors of all hues. Purple-leaved Fennel, Purple Passion Plant, Snake Plant, Calathea, Aluminium Plant, African mask plant, and the all-season crotons! All of them embellish colors so exotic that one cannot pass them by without noticing. It is mundane that the new shoots and leaves of many plants brightly parade in purple or red. These newborns however get clad in green as they grow. We all know that the plants bear multi-colored flowers to attract pollen-carrying insects and birds to facilitate reproduction. However, the leaf color does not have such a crucial role to serve. Nature has some very different purposes in mind, it seems.

The shoots of many plants are either red or purple. The color works as an invisible cloak that protects these delicate plant parts from sun damage. Anthocyanin is the pigment that gives leaves red or purple color. It is the sunscreen of these newborn beauties that we call shoots. Scientists believe that chlorophyll literally hides behind this mask to protect itself from sharp sunlight. Being stated that, there is still much ambiguity surrounding the reason why shoots or leaves of plants have colors other than green. One hypothesis also says that the leaves that stand to bask in strong sunlight are those that display non-green colors. Another one says that anthocyanins are strong antioxidants and they help the plants to remain winter-ready. What about the tropical rainforest plants that have purple undersides? Given this anomaly, are we sure that sunlight is a factor?

Scientists say that the red or purple color hides the shoots and leaves from the prying eyes of the predators which include pests as well as bigger herbivores. Studies have shown that red leaves get less devoured by herbivores when compared to green ones. Phenolic, which is a resin kind of material present in high concentrations, in red or purple leaves, could be another reason why herbivorous insects and animals do not want to eat them. It is also scientifically observed that purple undersides of certain tropical leaves have the same function which protects them from fungal attacks, which is a big threat in the humid microclimate of a tropical forest. The herbivorous insects are found to be generally more attracted to the color green, than red or purple. Hence, colors other than green reduce insect attacks.

The differently colored leaves still can carry out photosynthesis as efficiently as their green counterparts because they have a sufficient quantity of chlorophyll in them though masked by the color pigments.

Come Fall, trees such as Maples, Aspens, and Sourwood literally start a riot of colors. It is basically in preparation for the ensuing period of dormancy made necessary by a hostile climate. What happens at the molecular level is that the anthocyanin pigment acts as a shade under which the chlorophyll is broken down and nitrogen from it is reabsorbed by the plant for surviving the hibernation time. There are also other factors that impact the fall colors of tree leaves such as temperature, humidity, and sunlight. Very low temperatures close to the freezing point in Autumn cause bright red color in Maple leaves. A cloudy sky on the other hand will enhance the saturation of fall foliage coloration.

Different pigment combinations impart different shades to leaves. Good saturation of both anthocyanin and carotenoid results in brown color. This is the case when the leaf is senile or fallen. If carotenoids and anthocyanins are the two prominent pigments, the color of the leaf will be orange. Above all, based on the pH value of the anthocyanin pigment itself, it exhibits colors ranging from red to blue. Bilirubin, the pigment that gives the yellow color to the skin, eyes, (and urine of those who suffer from jaundice), is also present in some plants and gives a yellow hue to plant parts. For example, the seeds of the white Bird of Paradise plant have an orange-colored fuzz on them, which is caused by Bilirubin.

When the leaves age, they turn yellow or red. When a leaf reaches the end days of its life, the chlorophyll in it breaks down allowing the plant to absorb back the nitrogen in it. Obviously, nature does not want the leaf to leave the body of the plant with the saved-up chlorophyll wasted. It is almost like the leaf giving its vital force back to the plant and crossing the rainbow bridge in an ultimate act of self-sacrifice.

The colored plants are the favorites of any indoor gardener. Science says that the variegated patterns on leaves, when they are just white and green, are caused by plant mutation. These plants are the albinos of the plant kingdom. And many of them are known air purifiers and make them an indoor gardener’s coveted possessions.

These amazing facts about leaf color remind us that everything in nature has a purpose that will be revealed to a probing eye. Studying nature closely might thus give us an ability to understand better the purpose of our own lives and all the inter-connections involved.