|MadSci Network: Botany|
I an not sure of the exact species of oak in the question. However, it must be either a hardy oak or a non-deciduous oak which would keep its leaves when other oaks and trees drop leaves. This preparation for winter or a dormant period involves reabsorbing all the useful materials from the leaf, hence the brilliant fall colors, back into the root and stem of the tree. This applies for those that lose leaves for winter. If the pin oak keeps it leaves the only real thing to be said is that the plant has evolved to that end. This would have required the tree to allocate resources differently from those that lose leaves and become dormant. It would also help if the leaf would not freeze and would be able to warm to a point at which photosynthesis could occur. Why questions are the hardest to answer especially when talking about the plant and animal world. I hope this information helps.
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