|MadSci Network: Botany|
Hello, I just noticed your long-standing question in the unanswered list, and I thought you deserved a response. The answer is that the difference between evergreen and deciduous trees in latitudes where there is winter is NOT in the chlorophyll. The chlorophylls are nearly identical. The difference is that pines and other conifers that bear needles all winter actually protect the cells in the needles from frost damage by making their version of antifreeze. Some of the delightful aromatic smells of pines, spruces, and balsams are due to the mixture of organic compounds that are constituents of the sap that helps protect the photosynthetic machinery from sub-freezing temperatures. The problem for deciduous trees is not that the light level gets too low in winter for their chlorophyll to function. They respond to shortening hours of daylight by shedding their leaves and shutting down for the winter as an evolutionary adaptation to the coming COLD, not the lack of light per se. I hope you find this answer, that you didn't give up on ever getting one. And I hope it answers your question. Paul Odgren, Ph.D. Dept. of Cell Biology Univesity of Massachusetts Medical School Worcester MA
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