Day 5 – The hidden messages in a leaf

The last day of the first week arrived much quicker than I realised. The week had been quite hectic, in a great way – brain power that I had switched off at the start of the holidays was well and truly in use again.

This morning, we went back to check on our pollen grains to see how our pollen tubes had developed from the day before. Sure enough they had definitely needed more time to develop on our slightly watery agar (NOTE: a tiny mistake such as a decimal point in the wrong place in a recipe to make agar can make a huge difference to experiment results!) We used a very fancy and presumably very expensive and therefore definitely not something we will have access to in many schools, microscope to examine the pollen tube growth, and see them in real time on the computer screen. This was really beneficial as we got to make a montage of the images to take with us that will definitely be used in the classroom to show the growth of the tube.

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Next on the agenda was a walk around the college campus to collect different leaf samples with Karen. As our coordinator, we had been checking in with Karen all week but hadn’t worked directly with her so this was a chance to find out more about what part she played in the project (http://www.ucd.ie/plantpalaeo/bacon.html). The walk took us to one of the lakes on the campus, where we gathered several different leaf species from woody plants, with the hope of using them to estimate an average temperature, among other climate statistics, for the area. Now here you might think, why not just check in with Met Eireann for such a detail, but the whole point was we were to do this ourselves! I couldn’t honestly see what a leaf could tell us about this but we were not the experts and so myself and Louise dutifully collected bags of leaf samples and answered questions put to us that made me realise exactly what my students must feel like when I am asking them something they feel they should know but don’t. (Example: What is a plant? We found that it is actually quite hard to define but yet seemed so straightforward in theory. How would you define a plant?!) 

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With the leaves gathered under a hot midday sun, we decided an ice cream break was in order. Karen discussed what we would do next in the lab – identify the species of plant by their leaves (Easy, there were lots of common things such as sycamore and ash in the bags) and then classify the leaves based on their appearance (Again, surely not tough? Leaves were green and of a few different shapes yes? Where could the hassle be in that task?)

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So. As it turns out, leaves are not all as similar as we thought and you do NOT automatically know everything about trees because you can identify the four that line your own driveway at home! Karen lulled us into a false sense of security by leaving us with a book promising to  tell us everything we needed to know about leaf shape and identification and then left us to see just how difficult that task was. We turned leaves up and down, studying them as if some secret words were embedded on the under surface, we downloaded a phone app that promised success if you took a picture of your leaf and uploaded it (false advertising, they gave us twenty possible options for every different leaf!) We eventually had a larger pile of unknowns than ones we did know, and with everything starting to look like it had a green tint to it, we decided it was lunch time.

When Karen, with Caroline, eventually rejoined us, we were forced to accept the experts help on the matter!

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Karen then showed us how to use CLAMP (Climate Leaf Analysis Multivariate Programme), found here online (http://clamp.ibcas.ac.cn/). This demanded that we study the leaf in much more detail. Did the leaf have teeth? (Yes, that was a question!) Were they close to each other? Had it a pointy or rounded tip? Was it wider in the middle? How did the leaf and stalk join? All of these were important observations needed to enter onto the data sheet to show a link between leaf form and climate in the area at that time and this is where fossils are used in climate predictions. (For example, toothed leaves correlate with colder climates).

Amazingly, when we entered our information, our result was just one degree off the average temperature for the last twelve months in the area, which really impressed us. It was one of those moments you sometimes have in science where the data collection can seem tedious and you wonder, am I really going to get something worthwhile from this, and then suddenly you see the results and you have a real Eureka! moment. Without doubt this is something I will be utilising in the classroom, most likely with a Transition Year group. This was really eye opening stuff and the end result was definitely worth waiting for.

And so ended the first week of the course and I headed away from UCD for the weekend and home to tell everyone of what we had seen and done behind the closed doors of a research lab. Interested in plants or not, the family were about to see a whole new side to plant biology!

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