Among the numerous meanings of the word flush there are two to do with botany. The fresh growth of young leaves in trees and such newly emerged leaves are referred as flush (as a verb and as a noun). These are not commonly known even by native English speakers and some of them flush at times hearing it from me for the first time. I think this word is quite appropriate to describe the young leaves of trees in the rain forest that appear in red or shades of red.
Nathaniel Dominy of the University of Chicago and his colleagues pooled existing information on the leaves of hundreds of tree and shrub species from Central America, Africa and South-East Asia and discovered that in as many as 62% of them, young leaves tend to be coloured anything from pale pink to deep red.
Red is a colour of warning in nature. The young leaves lack chlorophyll the green pigment found in mature leaves and are packed with toxins that are distasteful for leaf eaters. The bright red colours therefore work as a warning to repel folivorous (leaf eating) animals from making a meal of them. This gives a chance for the young leaf to grow into a mature stage to fulfill its duties of photosynthesis and transpiration. The reddish hues are also capable of reflecting harmful UV rays of the sunlight, than absorbing them, protecting young leaves with such colours further from the effects of sun.
As the leaves mature they turn less red and more greener – often taking yellowy-green and reddish-green hues. (It is those leaves of intermediate stages that folivorous animals such as Leaf-Monkeys pick for their diet).
A good example for such a tropical tree with reddish flush is Na (English: Iron Wood tree), which is botanically known as Mesua ferrea (formerly, M. nagassarium). This tree is native to Sri Lanka and is also named as the National Tree of Sri Lanka.
When we talk about plants and animals, we use the terms “native”, “resident” and “indigenous” generally to refer to ones that are found in country/territory as natural breeding populations but is also found in another country/territory the same way. The term “endemic” in contrast is used to refer when a plant or an animal is restricted to a particular geographic area – in our case, Sri Lanka.
Sri Lanka is blessed with over 3,600 flowering trees and plants that are termed as native/indigenous/resident out of which nearly 900 are endemic. I know it does not matter too much for world peace, but with such staggering endemism, I think we should have an endemic tree to represent as our National Tree. No?
In this respect, there is no better tree to be named a National Tree of Sri Lanka than Diya na – an endemic Ironwood beauty found in the lush valleys alongside streams in the rain forests in Sri Lanka, botanically known as Mesua thwaitesii (formerly, M. ferrea).
I have planted two Diya Na trees in my garden – one older and one younger (now aged 8 & 6 years respectively). The older one, which was about 3 feet tall when I bought it, was planted in a spot exposed to direct sunlight. The younger plant, which I got two years later, barely a foot tall, was planted in a shady spot. Most rain forest trees need shade at their early stages of growth. Proving this point, the younger plant has now grown very much taller & broader than the older one and looks in really good shape.
The picture at the top is an extreme close up (shot at 3 times the life size, if I remember right) of a young leaf of Diya Na, matured slighly to lose the deep purplish red hue seen in flush at early stages, as in the picture below.
The surrounding green represents the colour of the leaves when matured.
Note for native readers: The prefix “Diya” in Diya Na as you know refers to water – as this tree grows in riverine habitats. When you isolate the word “Na” I am sure you will agree that it gives a meaning approaching “bathed”. Combining these two meanings, I like the how the name Diya Na sounds in literal sense as “bathed in water”.
When I glance at a Diya Na tree in late stages of flush for long, the dense, droopy clusters of its elongate leaves with their slightly scalloped margins and beautiful highlights created by the flush make the poet in me see them as long dangling hair of a brunette who has bathed at the nearby stream and has just wiped her curly hair clean.
These are the kind of things I think when I am marooned in rain forests with too many male bird watchers.
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