This is the question that plagues me this morning as I contemplate the still-growing tendril of ivy in my dining room. While outside, the temperatures are well below freezing, and have been for days. How is the ivy continuing to thrive? Is this kind of ivy hearty enough to survive a northeastern winter? Is this tendril it's own separate plant, now, with roots warm enough tucked away in the warm-enough window casing? What possibilities am I missing?