Why are new msasa leaves red?

Throughout the year if you are in the bush and look around you will see pink growing shoots on sapling Msasas. What is amazing, however, is that the trees all come into a full set of new leaves well before the rains (in September). Msasa trees lose their leaves, sometimes for only a matter of days, and then burst into new leaf. The colour of the new leaves varies from pale pinkish fawn though all the shades of pink, orange and red to deep maroon and the woodland is a wonderful sight especially with the sun shining through the leaves. And being a scientist I have to tell you the reason.

Normally leaves appear to be green in colour because they absorb red light and reflect green light, the complimentary colour. When the light is very intense, however, and the tissue very soft, as it is when the leaves first open, they could get burnt, so they have a built-in sun screen, a pigment called anthocyanin that colours them red and protects them.  As the leaves expand and harden, they no longer need protection and change to green.

One of the interesting aspects of leaves that flush red is that they are still able to photosynthesise and produce food. The experiments done on Msasa leaves showed that they took 25 days to become mature and fully expanded and further that the chlorophyll content of the leaves increased steadily during those 25 days.  The anthocyanins also increased but only for 23 days and then rapidly decreased. The articles from which I have obtained this information, mention that anthocyanin is water soluble, so presumably it dissolves and fades away.  One therefore assumes that the tree should have at least some colour, other than green, in their leaves for over three weeks. The leaves then turn a lovely soft, gentle green and at the same time the Msasa come into flower.

One question, which always arises, is why are the leaves different colours from one tree to another?  The answer is that trees flush at different times and so start red at different times, therefore becoming green at different times and secondly, of course, there is genetic variation.  We have different colour eyes and different colour hair. Why shouldn’t the plants have different colour leaves?

– Meg Coates-Palgrave –

(writing for Bamabazonke Nhasi a couple of years ago)

For further information – see the video below.