Thursday, June 24, 2010

Dillenia excelsa var. tomentella: A new phenotype arising

Perhaps I ought to qualify my sub-title with a question mark, but I decided not to. I am quite willing to bet on my belief that a real significant change is indeed happening to this one tree - yes, this particular wild Simpoh tree in the rain forest of MacRitchie.

By all account - the leaf, flower, fruit, and tree structure - the tree is Dillenia excelsa var. tomentella; all, that is, but for one dramatic difference - it is flowering without petals. It ought to have but it has not. Never have I come across a tree of this species behaving apetalously.

In the course of my investigation, I visit the tree ten times within two consecutive weeks at different period of the day hoping to sight a flower with petals intact or fallen on the ground, but none whatsoever. Then, on the tenth day, after a much exhaustive search, I managed to find one on the forest floor.

This singularly detached petal, however, is abnormally small and hardly matching the documented size to say the least. It is even smaller that the sepals produced by the tree. For good measure, I opened up the few mature flower buds I could find but found no petals within any one of them. [Detailed photos below]

So, change is afoot though not a complete one. I do believe a new phenotype is arising but not quite there yet. As to what caused such a response from the tree, I do not know. Mutation? Effects of the environment or climate? A geneticist, a chemist or a climate scientist can tell us more. This tree certainly presents itself an opportune subject for scientific studies outside the confines of classical taxonomy, e.g. ecology and climate science.

The important test is, of course, sustainability of this new apetalous character. I would like to confirm it and also prove the viability of the seeds if any. The coming flowering seasons should hold the key.

Relative size of flower; sepals 5, white with tinge of pink, fleshy and waxy.

Buds and open flowers: no yellow petals in sight.

Some mature buds found.

Buds opened for investigation: no petals found.

Result of a 10-day search: one abnormally small petal found.

Leaf elliptic, densely hairy beneath; leaf blade 8 to 10 inches long; margin entire.

Leaf stalk densely hairy; 2 to 3 inches long.

Leaf stalk deeply grooved above.

Bole straight; bark smooth; buttress roots none.