One of our mature Oak trees never sheds any leaves in Autumn but instead sheds them complete with whole twigs, some up to 2 foot long. I notice this year another Oak which normally only sheds leaves, has this Autumn decided to get rid of the whole twiglets as well. No leaves fall on their own without the accompanying twig,

This seems to be a genetic response, perhaps to growing conditions/weather and is a kind of self-pruning to keep the nutrient uptake in balance with the growth.

The twigs are not snapped but are shed by the tree in the same way as leaves are; that is by the abscision layer of cells that ‘cut’ the twig from the tree. I am not aware of species other than Oak which do this but would be interested to know if others have seen this. On the photos you will see the rim and the neat abscision at the end of the twig. The convex end fits neatly into the cup left on the tree branch.