Question

Why some plants have red leaves or leaves with yellow patches?​

Answer 1

Answer:

some areas of the world, the weather changes in the fall, making the air turn cold. During this time, many leaves also change colors. Why does this happen?

image of dormant tree

Deciduous trees drop their leaves in winter. Image by Paul Buckingham.

First let's think about why some trees drop their leaves before winter. In the winter, it would take a lot of energy and water for plants to keep their leaves healthy. But winter is cold, dry, and usually there isn't much sun (which helps give plants energy). So, instead of trying to keep their leaves, some plants drop their leaves and seal the spots on their branches where the leaves had been attached.

How is this related to what makes leaves colorful?

Leaves are colored by molecules called pigments. The pigment that causes leaves to be green is chlorophyll. Chlorophyll is important for plants to make food using sunlight. During spring and summer when there is plenty of sunlight, plants make a lot of chlorophyll.

In autumn when it starts to get cold, some plants stop making chlorophyll. Instead, those plants break down chlorophyll into smaller molecules. As chlorophyll goes away, other pigments start to show their colors. This is why leaves turn yellow or red in fall.

orange colored leaf

In fall, plants break down and reabsorb chlorophyll, letting the colors of other pigments show through. Image by Sander van der Wel.

The color change usually happens before the leaves fall off of the tree. Why might that be? It takes a lot of energy to make chlorophyll. If the plants break down the chlorophyll and move it out of their leaves before the leaves fall, plants save energy. The plants can reabsorb the molecules that make up chlorophyll. Then, when it's warm and sunny enough to grow again, the plants can use those molecules to remake the chlorophyll. That way the plants don't have to make chlorophyll from scratch

Answer 2

Some plants stop producing chlorophyll in the fall when the weather becomes cold. These plants, however, disassemble chlorophyll into smaller molecules. The colours of other pigments begin to emerge when chlorophyll disappears.

This explains why autumnal leaves turn yellow or red.

Red foliage:

• The pigments known as anthocyanins are what give the colour red.
• The pigments also contribute to the blue of blueberries and the black of soybeans in addition to the red found in certain leaves, grapes, and onions.
• Some trees have a high concentration of these pigments in their natural state and will always have vibrant colours.

Yellow spots on leaves indicate:

• Yellow patches between leaf veins on elder leaves are the initial sign of magnesium shortage.
• Veins continue to be green while the leaf's core turns yellow.
• The leaf's edges are yellow last.
• Yellowing between leaf veins is another sign of iron shortage, but young leaves on plant tops and branch tips are initially affected.

The numerous types of pigments found in leaves are what give them their various colours. The plant leaves contain three different types of primary pigments. These pigments give the leaves their various colours. They are anthocyanins, carotenoids, and chlorophyll.

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