School students show hairspray keeps Christmas trees alive longest Getting it right: Students Emily Scarlis 11, Lilla Szentmariay, 13, and Madison Dixon, 12, working on their study. About this time last year, scientist Angela Moles was erecting her family Christmas tree and wondering how best to keep it alive and looking fresh. I was thinking of all the myths, are you supposed to cut the bottom off, are you supposed to water it with aspirin or hot water? I wanted to know what works best," said Professor Moles, from the University of NSW. Like a true scientist, the plant ecologist suspected the quandary could be solved with a simple experiment. The students found hairspray, more than water and beer, kept the cut branches alive best. She took the challenge and a freshly cut pine tree, to the year 7 girls of Kambala School in Rose Bay. The willing lab assistants decided they would treat branches with one of four remedies: beer, boiling water, energy drink or hairspray. Another group of branches were fed water as a control. The results were surprising. Like humans, plants don't fare well on a diet of beer. After 27 days of drinking VB, the branches were limp and brown. Those fed with energy drink suffered a similar fate. The control and boiling water treated branches fared better. But it was the branches tended with hairspray that survived the longest, retaining 90 percent of their ability to photosynthesise after a month. They even sprouted new needles. While Professor Moles admits the "treatments" were not typical plant food, the girls had sound reasoning for their selection. "We thought the boiling water would break up the sap at the bottom of [the tree] allowing more glucose to come through," said eleven-year-old Emily Scarlis. As for the beer, well, "a lot of people have beer at home leading up to Christmas lunch and it also has lots of nutrients so we thought that might help keep it alive and the alcohol may kill off any germs," said Lilla Szentmariay, 13. Sound reasoning, indeed. The girls used an instrument called PAM to monitor the plant's health over time. The device shoots a beam of light at the needles and then measures how much light is absorbed, an indication of how efficiently the plant is converting light energy into chemical energy to make sugars and starch. Professor Moles suspected the hairspray kept the branches alive for longer by blocking the plant's pores, allowing it to retain more water. But the hair product may also have blocked the plants' ability to detect a chemical hormone called ethylene, a gas that tells plants to start aging and for their leaves to drop off. "When you get a stinky banana that makes all the other fruit go rotten that's the ethylene acting," said Professor Moles, who visits Kambala as part of a CSIRO initiative, Scientists in Schools, to expose students to real scientists. The class has written up their results to submit to a peer-reviewed journal.