For over a hundred years the genus Myriocarpa in the nettle family which comprises ca 15 tree species in South and Central America has been impossible to place within the family. This is largely because of the very unusual shape of the part of the female flower that receives pollen, known as the stigma (see image below) and the fact that neither of the two great experts could agree over whether the petal-like structures at the base of the flower were petals associated with the flower, or bracts associated with the stalk. Whilst this might not seem like the stuff to keep a botanist awake at night it has become of interest again as using DNA data we have identified as sister to another small group of trees, Gyrotaenia, found in Cuba, Hispaniola, Jamaica and Central America that has a flower which consists of the petals fused to form a tube which is fused to ovary.
I was therefore very curious to see whether Vladimir Blagoderov, Manager of the Museum’s Sackler Imaging Suite could help me generate an image that would help us resolve the mystery. He could! The two images above are each composed of about 20 images which ‘slice’ through the sample which was of young flowers collected in alcohol in Belize over 10 years ago. The resolution was amazing, each cell being visible. In fact you could even make out the rough crystalline structure on the surface of the hairs! Both of these images also helped us to answer the question, revealing that this flower does indeed consist of a tube composed of fused petals that is subsequently fused to the ovary. This we could see in both images where the clearly visible ovary is enveloped by another distinct tissue, as in the case of Gyrotaenia. It was also confirmed by the petal-like bracts at the base of the flower having stalked glands, structures not known to occur on the ovaries of Urticaceae. So a morning’s work and an idea of evolutionary relationships enabled me to answer a question that had been frustrating an albeit very small group of botanists for over 100 years!
The synthesis introduces two concepts that were new to me: the first was the notion of the Amazon as a ‘Green Ocean’, the second that the Amazon functions as a biotic pump pushing ca 20 billion tonnes of water into the atmosphere every day and in doing so drawing water vapour in from the Atlantic Ocean. The first idea of the Amazon as a Green Ocean is an important one as it gives a scale to the impact the Amazon has on the global climate, equivalent to one of the World’s Oceans. Conversely it also suggests the enormity of what we are doing to an ecosystem that is probably critical for our welfare. The second concept, not proven but for which there is mounting evidence, presents the Amazon as a vast community of ca 385 billion trees mutually interdependent with trillions of micro-organisms, insects and vertebrates functioning in concert as a water pump, extracting water from the ground, catalyzing its conversion to rain in the lower atmosphere and in doing so drawing water vapour in from the Atlantic Ocean and sending moisture to the grain belt of South America creating one of the most productive agricultural landscapes in the World.
The main points of Antonio’s report are that 1) the Amazon generates a climate that supports agriculture to its south, 2) deforestation will result in a climate that does no longer supports agriculture in southern South America, 3) that the nature of the Amazon’s impact on climate means that there is a point of no-return with respect to deforestation which once passed will lead irreversibly to desertification for much of southern South America, 4) that deforestation in the Amazon is already having an impact on the regions climate and that this could accelerate the impact of climate change on the Amazon, and lastly 5) it is not too late to reverse these impacts and that muscular actions to outlaw forest fires and deforestation coupled with a popularization of the scientific research on the Amazon cold avert the destruction of the Green Ocean. I can not recommend reading the report enough, it is engagingly and precisely written and will make you amazed at the impact forest have on our World.
Alex Monro's blog about the documenting and conservation of biodiversity