Tuesday, 8 April 2014

Signing up to chunky flowered trees in Singapore


The Autograph Tree is so named because you can scratch your name on its leaf and that autograph will remain for the life of the appendage. This is probably true of most leaves but in this case the leaf survives your mutilation.

There are over 300 species of the leathery-leaved Clusia, the Autograph Tree, all from the tropics of central America. Many start as epiphytes, plants attached to other plants, but in time they overwhelm their host with roots and form their own trunk, much like the strangler figs.

There are separate male and female flowers, but both occur on the same individual. The flowers are as chunky as the leaves, often looking like porcelain or wax.

Some grow as mangroves, including the plants I'm featuring today, Clusia minor.  A mangrove is not a taxonomic category but a life form. Mangroves are a group of about 50 species that occur in intertidal mudflats, surviving inundation by salty water twice a day and often producing roots that seek out fresh air above the sea.


I photographed these relatively young Clusia minor (they grow to 10 metres in height) from the foreshore at Gardens by the Bay, in Singapore. They look to have been planted in the last couple of years. The species is native to the dry savannahs of Caribbean islands and mainland Central America but planted throughout the tropics.

I was captivated by the flowers. Firstly by their texture and shininess, then by their odd structure. I just couldn't work out whether they were the male or female flowers I was seeing, and just what was what inside that highly polished bloom.


There were no fruits, unfortunately. This is a picture I've copied from a fascinating blog about the plants of Panama. It's also the source of my initial identification (as Clusia pratensis, now considered to be the same as Clusia minor).


My Panamanian blogging colleague, Mary Farmer, had sought advice from Missouri Botanical Garden. Among the diagnostic features of this species given to her were that the flowers don't produce stamens (the male, pollen-bearing parts). Now the female flowers wouldn't be expected to produce them anyway but I couldn't find any flowers with stamens.

As Mary points out, the green blob in the middle is the female part, where pollen would normally land and stick for fertilisation. The sticky brown circle is presumably a ring of nectar to attract pollinators, although they have little to do in this species. It produces fruits without fertilisation it seems.

I'm still not quite sure if Clusia minor bears only female flowers, or whether there are male flowers that appear occasionally and perhaps they are infertile. Always more to learn, which is just fine by me.


While we are on the subject of quirky, chunky flowers in the parks and gardens of Singapore. I can't resist a few pictures of the Cannon Ball Tree, Couroupita guianensis. This is unrelated to our Clusia (and to what is called the Cannonball Mangrove) but it does have rather spectacular flowers.


In this case they turn into cannonball like fruits that split open to release a foul odour. You can see them all over Singapore, even as a street tree, but this one is inside Gardens by the Bay. Yet another reason to visit!

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