sarahkeenihan

Posts Tagged ‘sap’

And speaking of poo…

In November 2013 on November 30, 2013 at 8:48 pm

Kirsti honeydew Ultracoelostoma Noble text

Kirsti: Earlier this week, Mia wrote about POO POWER! I too have a story about the science of poo.

Lots of insects feed on phloem, a.k.a. plant sap. And just as we excrete waste from an omnivorous diet as a conglomerative breakdown of those foods, sap-sucking creatures such as scale insects, aphids, psyllids and others  poo honeydew, the waste from the sugar-rich foods they ingest.

Even further down the food chain exist microbial communities that survive on the honeydew (poo) that makes its way down onto the surface of leaves, which are little ecosystems in their own right. If you live there, you live in the phyllosphere!

We don’t know that much about life in the phyllosphere. But recently some scientists in New Zealand looked at fungi from the phyllosphere of native beech forests in New Zealand. Endemic scale insects that live on these trees produce up to 4500 kg  dry weight/ha/year of honeydew.

The insects use an ingenious method to keep themselves clean and minimise fungal growth on their bodies:  the honeydew is flicked off the end of an anal wax-tube (as shown in picture).

Together, all the excreted sugary delights from these creatures  fuel the growth of an abundant mould. The mould appears black and kind of powdery from afar, with human eyes. But look closer – a LOT closer, down a scanning electron microscope then even closer at their genes – and you will see a circus of species, a kaleidoscope of colour, most of which cannot be identified!

The study that identified these fungi communities in New Zealand emphasises that despite the sooty mould being such a ubiquitous element in the scale insect-beech system, we know very little about the microbial diversity. The conference I have just been at highlighted the same gap in knowledge for ecology in general.

So people, let your imaginations run wild! Poo of all sorts of species powers communities, even if it’s a microscopic one in the phyllosphere.

Oh, if you’re interested in microbial communities supported by your own body, I’d highly recommend reading The Wild Life of Our Bodies by Rob Dunn, a fantabulous science writer from North Carolina State University.

[image thanks to David Noble]

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Day 112. Bloodwood

In December 2012 on December 2, 2012 at 8:17 pm

 red sap

A morning walk for French pastries turned into a journey of discovery today when we happened upon a large Bloodwood, or Corymbia tree.

The lower half of the trunk was covered in deep red, quince-paste-coloured crystals and solidified drips of sap – we collected a few samples (shown above).

The tree itself appeared rather different in terms of bark and leaf characteristics compared to other native Australian plants I could see in the street, so upon returning home I performed a little research.

It turns out Corymbia is indeed a Eucalypt, but its relationship with other trees in the genus is complex. Jim Barrow at Australian Plants online tells an interesting story about Corymbia, and in doing so sheds some light on the processes botanists use to classify plants and describe their evolutionary relationships with each other. I’ll leave it to you to read the full story, but the bottom line is there can be two approaches to thinking about plant classification. To quote Jim,

“Fundamentalists argue that classification must follow evolution. If the branching structures created by computer programs show one group branching off and then another group branching from this, this must be reflected in the names given to the groups.”

“Pragmatists say that classifications are generated by humans for our convenience and a genus is a grouping of questionable natural significance.”

I’d love to study plant – and indeed animal- classification. My impression is that it would be a walk through history as well as biology.