when is a tree not a tree?

these old apple trees are on the farm just up the road from my house. The trees are bent - and as in this case completely hollow, but still keep on blossoming in Spring and, as per Keats in Autumn the "mossed cottage trees" are bent with fruit.
The farm is a refreshing exception to the surrounding fields which belong to a large estate which tends to favour monoculture. Here there are chickens, pigs (sometimes so free range they stop the traffic!), wild flowers, potatoes and more. It all looks very idyllic.